how hard would it be to use a program like say google sketup to make models then sum how upload them to the game.Just a idea becouse then u could have people make like towns and stuff and upload it to the game or whatever. or should i shut up because im a noobie and have no idea about game design

For objects, items, clothing, towns, etc... the game will be the editor. Since all of those things will be buildable in the game itself. There is no reason for an external model editor.
There will be a process for exporting them (already is for objects, actually) and then turning them into mods. I also plan to have a "mod store" where people can upload their mods for others to download. To include having it automatically download mods if you want to play on a server that requires mods that you don't have yet.