I cannot speak for Conitec because I am no member of them. Generally, though, it seems that the manpower Conitec has, is used solely on Gamestudio. If you would make one or more of them work on a high quality demo, this would decrease the development of Gamestudio.

So, Conitecs policy in the past was: if you make a demo which has a certain degree of quality, Conitec bought it and presented it to the public (or they specifically hired people to do that).

Community projects are very rare and more rarely successful. I dont think that this is a business model for such a production. If there is a group of skilled people: do a very nice demo, talk with Conitec for the financial part and do it. You need skilled people for a skilled demo. Period. The same with games and all that stuff, btw.

Such demos are also very visual-driven (at least nowadays), so you need a clear image what you want to do from a designer perspective, so you first need people who are skilled enough to develop a train-of-thought for the visuals of such a demo. This could be done by sketches (good ones!), a storyboard, a document, etc. So, if this fails, you should'nt proceed. The Venice and the WW2 demos are not really that what you can call a good demo, but they are nice to look at for the first 20 seconds until you see that they are "dead" and not taking much advantages from the engine.