A lot of developers cancel. It's been happening since the beginning.
The big companies with the great games stick. The small companies with the crap ones don't. So it's a filter. No worries then.
If I get a next gen console, it'll definitely be PS3. 360 wont get GT5, Winning Eleven, and Tekken 6 for sure. Those are really important exclusives to me. Throw in Virtua Fighter 5, Devil May Cry, Castlevania, Final Fantasy, and Metal Gear Solid. I think that's enough to seal the deal.