Unless apple sticks some real GPU power in an iMac us mortals can afford.......why bother. Hell for the price of an iMac you would want you can get your self a mini, an air, and have enough change left over for a wii u or an xbox or something.
I think I am going to follow this advice. I am puttering along with a late 2011 15" MBP and it can still mange to run XCOM2 albeit with some huffing and puffing. When it finally kicks out, I am hoping a new/refurbished Mac mini will seem face-meltingly fast by comparison, even with an integrated GPU. The Air can then take care of any mobile, work-related document tinkering and web browsing.
SOME MORE TIME AND THOUGHTS AND A LITTLE RESEARCH LATER: That integrated graphics ! The best thing for my lite gaming might be to just pick up a refurbished 27" iMac for under $1500.