Not for a while.
For starters I currently mirror my projector with my monitor and that becomes a lot more effort if they're different resolutions. So unless my situation changes I shall probably upgrade when 4k projectors are cheap enough, and they're a long way off.
I would probably have bought a 27" 2560x1600 or similar last year instead of my current 1080p 23" if it weren't for that.. worth it though for that home cinema setup
Gaming is a non-issue since if you don't want to shell out £££ on GPU power, drop the res down to 1080p which is plenty high enough for good quality and enough to tax mid-range GPUs with high quality settings and enjoy perfect scaling (each rendered pixel fills four pixels exactly)