First of all, thank you Mark for really taking the time to discuss this in a forums such as this. As a gamer that has really enjoyed things you have done in the past, its really great to see this. Also, I've been reading K&G for a long time and decided it was a good opportunity to post some feedback in this thread.
I would first like to go over what your initial post was requesting and then go over some general things that pop in my mind.
Deal Makers- Large/Living/Immersive World -
Really this is a lot more than one thing but together I believe it should be 1 thing. MMOs today have such a hard time with this because everything is so linear. The further out from your city you go the more difficult it is. That just doesn't make sense. There are also things such as being a seasoned adventurer and you come across a bug, that if it were to come to your home town where you started would destroy everything, but because you're 5 zones away it is normal. This also makes no sense and destroys immersion.
Another thing that destroys immersion to me is just how the internet has changed us in the last 15 years. My first MMO was EQ. When I first logged into that game, I had NO idea what was out there. What is over that hill over there? Why don't I just go find out. Nowadays, people just pull up the in game map or a map on their second monitor. There is so much information that floods out to the internet, it's so easy to just look things up. There really isn't a way to stop people from posting maps and such, but I think that in game maps and such really take away from that sense of being in a large world and really not knowing what's around the corner.
As far as a living world, I think GW2 has done the best job of doing something close to that with their events. The game would need to make actions of the players have real consequences to the world. If a band of npc bandits go and attack a small village where players go and sell some loot to a merchant and kill said merchant, the players won't be able to sell there until they take back the village and another merchant travels there. Things like that make the game living and actions of the players have consequence.
- RvR with Purpose -
Sadly, no game has done this since DAoC. Even then, I think there is a ton of opportunity to expand tenfold to what that was. I have had daydreams of how I would make an RvR system that I would love. Imagine a game where the contested land is across an ocean. Crafters would make ships that would be used to sail there (more on that later). There would be naval battles to control the seas but once you made it to the contested lands, you would battle over key areas. If you controlled that area, you'd have access to dungeons or materials for crafting only found in that area. If a realm wanted access to those, they would need to control that. After a set time, if it;s been in control by the same realm, it would reset to neutral and powerful NPCs would take it over. The realm would no longer have access to the riches of that area. These resources would also need to make it back to the main land for the crafters to use. Realms would need to keep trade routes open. If they are broken, anything that is split off and doesn't have access to the main land wouldn't be able to make it back so the realm would need to take that back. Players would also want individual rewards for participating in the RvR combat. There you get into trying to keep it balanced so new players coming in don't get discouraged by someone so decked out that he could kill a whole group by himself. I don't have any suggestions for that one yet

- Crafting that isn't just a money sink -
Crafting in modern MMOs just seems like a money sink IMO. Sure, there might be a few useful things that people can make once they are maxed out, but not enough to make people just want their primary profession to be a crafter. As I mentioned above with the ships, I think crafters should be highly important to the success of a realm. Crafters would have to be the ones to create the ships to sail to the contested areas, build up the player cities, build the fortifications of the keeps in the contested lands, make the highest grade armor/weapons. Why does that dragon need to drop a breastplate? Sure, I know people get excited for rare drops but why can't players harvest for his scales and teeth etc that are used by the crafters to make the awesome equipment? I would be just as excited if I killed a dragon and was able to harvest a pristine dragon tooth off of him and know that a weaponsmith could turn that into an amazing weapon.
Deal Breakers- Modern MMO Questing -
GW2 was a nice breath of fresh air away from the linear questing model. Nothing destroys my immersion more. I'm sure there is very very few people that would even read them. They just look at their quest tracker and the mini map and go. I would love to see quests be very long drawn out journeys like they had in EQ. If its just go to quest hub and talk to everyone with an icon and move on, no thank you.
- No housing -
Again, this is part of the immersion thing that I'm looking for. I like a place to come back at the end of playing and to put my loot in a chest and hang my trophies up on the wall. SWG was the king of housing and sadly, I don't think I'll ever see something like that again. Prove me wrong Mark!
- Themepark -
We all know what this means and we all dislike it so I'm not going to go on and on about it.
Some random thoughtsWell, I didn't think I'd be typing this long so I'm going to keep this short. I saw a lot of people talk about instancing. Instancing can get over used really easy, but in todays market, it's really hard to not have it. There are so many players now compared to the early age of mmos. It's just not realistic to have an open dungeon with 100s of players in it. Having smaller open dungeons spread out over the world would be good, but I think main ones would have to be instanced. This also helps by being able to tell a story better for that dungeon. SWTOR did a good job at that. You knew why you were doing something in a dungeon because there was a story for it.
I also think it's time to move away from character levels and more to skill based. Imagine a game that has no levels, but "age". Your character ages every real life week. The way you advance is by using your skills (EQ style, the more you use it the better it is). As you advance your skills, you unlock abilities based on that skill. Each skill has several paths that basically determine your "class" For example, when you reached your skill milestone you unlocked 3 abilities. One of those abilities is a taunt attack another is an increased damage attack. So if you were wanting to be a tank, you'd obviously take the taunt attack.
Once your character reaches a certain "age", you may create an offspring(alt). This offspring would gain certain benefits based on his or her parent. Eventually over time, that offspring would then be able to do the same. Over time, a person could create a really unique character.
If a person chooses to for-go that option, they could have their character become a "Paragon". This would be a quest the character has to complete for their gods which unlocks a whole new set of skills. This would allow someone to stick with their Main and not be affected by age. Speaking of age, after a certain time, your characters skills will start to degrade as would yours in real life.
Anyway, sorry for the wall of text. Looking forward to further discussions!
TLDR: blah blah blah, I miss old school MMOs and want that feeling again, with a twist.