I quite like MMOs of a more instanced design, such as Dungeons and Dragons Online, or Guild Wars; I like to be able to interact with other people in public areas, but when I’m off adventuring with a party I like the fact that I won’t have a bunch of loljumping twits training mobs onto our group as we try to fight a boss.
Taking the instanced design as read then, I thought it Quite Interesting to consider having two different game engines depending on the space the player was in. For the adventuring and dungeoneering side, a detailed graphics and game engine could be used that could only handle a party of six or so players due to technical limitations (something like Vindictus which uses the Source engine) allowing environment destruction and very detailed character models which would otherwise be challenging in a highly populated game space. On the public side, a different style of engine could be used, one able to handle hundreds of players in a communal area. Perhaps a different perspective could also be employed here – such as a JRPG/Diablo isometric-like third person – which would demarcate the two areas and avoid a continuity clash in the players’ perception of the world’s detail level. The isometric world would contain dynamic player housing, crafting games, player shops, and other such elements which are more easily employed in such an engine.
There would be plenty of hurdles, obviously: avoiding having to translate between the engines for items and gear would be one, but characters could have casual cosmetic outfits which they wear in public spaces that would differ from their adventuring outfits, for example.
With a strong demarcation it would then be possible to concentrate on the social side of MMOs in the populous isometric world, while allowing the more intense gamer side to be fully expressed in the traditional group-orientated third person instanced areas, but at the same time providing continuity between the two communities (crafters providing equipment for adventurers, for example) and thus hopefully encouraging interaction and migration between them.