Ok, all this gamemake idea is very cool and it's very impressive what you can do all together just starting from zero...
BUTAs other projects that users tryed to finish and they died... it's not the correct way. For example, there was a project called "Anim8or Movie" ( or something like that ) which ofcourse wasn't finished ( or better to say actually wasn't even started). And that's becouse they wasn't organized well. Just as example, one thing they was doing is to try find out which title for the movie will fit better and what the LOGO should looks like, but all these while they still even didn't know what movie they whant to do, what story, what ...everything
About the models: you should decide what you need and then ask it from some users, for example "the main caracter is man/girl/dog/bug
( big, small, cartoony, super-dooper
) and then every user will create something and there will be a big range of choice ( just imagine that for example for one good enough model you would spend one hour, but if in this one hour at the same time 10-15 people are doing one model each you will have 10 different models in time in which one person whould make only one). And all this only when everybody know what exactly to do. So, in summary, it must be declared what exactly is going on here, what's the story, who's the caracter, what he/she must do, what can do ( for example one knight fights some creations and try to get a magic stone which is on the last level in the castle
)Definitly it's very cool idea and it would be shame if it'll "die" .