I think it would be neat if more games were easily moddable, examples include half-life for it's complete toolsuite and trackmania for it's novice friendly map builder and resource downloader. In fact peer-to-peer games like TrackMania and half-life (counter-strike) offer a lot of advantages over more static, developer created games. What if the great games of the future were more of a platform upon which more casual story-games could be built by volunteers / users, in some ways like second life but with more focus... Perhaps something like game making tools that are games themselves, thus as users play they also create, making an almost infinite amount of content. It would be nice to be able to expose the game code itself to this, as well as all of the resources, with differing challenges to build each part of the game. In addition to building the game, of course people could play. Spore was an example of this in some ways, although the user creations were very limited in scope. Imagine if instead of only letting users mod the creatures in spore, if every part of it had a million user created options that were sorted by quality/popularity and automatically downloaded in the background silently. The code library alone would be a very interesting part, allowing programmers to potentially implement custom functions which could be referenced from the objects. Games using this design theory would of course allow anyone to host a server, although for MMO-like properties there could be a 'trusted' server option which would record characters/items specific to that server or cluster, although anyone could own or run one. The primary job of the company who makes a game on this platform is to design and create the platform itself, the toolbox itself that holds the initial tools and the tools to train users to play and make content with the base code as well as to coordinate effective distribution of the custom user content, possibly with a popularity/rating/time played system, along with layered server coordination, possibly with an 'official' server network, which could be joined by users with permission, however there could be 'unofficial' servers as well with server specific standards of testing, safety, censorship, and that sort of thing.

You mean like what Epic does with Unreal? Or what Blizzard is doing with Starcraft 2?

That is actually the model I've been designing my own game on. I fully plan on giving users the ability to build, within the confines of the core mechanics and engine, pretty much what they desire. It also means if I make a sequel/add on, I don't need much (if any) coding.

I think we can look to older games such as Quake and Doom, both of which had their source code released to the public. Both still retain active modding and gaming communities. Or to a lesser extent, the original Call of Duty and United Offensive, both of which have active modding and gaming communities.

However, I don't think you'll see a lot of sales if there isn't a quality game to showcase the engine and mechanics.

Modern games seem to be designed to eliminate communities however. Modern Warfare 2 eliminated traditional online FPS gaming, cutting dedicated servers for communities to grow in, the number of players per game cut to a mere 18, and thus far IW has refused to release any mod tools for it. Halo 2 just shut down it's servers, meaning there will never be anyone playing online again.

So, sadly, don't look to see any major publishers supporting the gaming and modding community. They don't care if a game is good, or can last 10-15 years in the market. So long as it turns a profit and sets up a profitable sequel next year.