"Unrealistic" would be something like Mighty No. 9's stretch goals to release on every platform under the sun. They got lots of money to do that, but actually doing it is a massive undertaking, both technically, and more importantly, logistically. (Of course, one could argue that trying to make a game for the 3DS and PC at the same time wasn't going to work because the 3DS is such a low power system, but the logistics are huge even without that.)
A lot of projects stumble because the stretch goals actually make the whole thing worse due to how much bigger the project becomes. I'd suggest that any "big" stretch goals be marked as "post 1.0" things, such that the base game is done first, and only then do we move onto whatever they are. Othrewise you either need a bigger team or to push the release date back an eternity, and both options suck.