I don't think the Fusion drive will be included but the price points will remain the same in my opinion. The 21.5" iMac is fairly easy to predict.
They'll use an embedded CPU on the motherboard that will come with Iris Pro 5200 graphics, all models of the 21.5" will lose the discrete graphics.
2.7 GHz quad core i5 for the 'good' spec.
3GHz i5 quad core for the 'better' spec.
3.2GHz i7 quad core with hyperthreading for the 'best' spec - a BTO upgrade from the 'better' spec.
You can expect them to retain the same case shell - the cpu has the same thermal profile - and the graphics will be a rough match for the discrete versions offered on the Ivy Bridge models GT640M and GT650M while actually producing less heat because there will be no discrete GPU.
Effectively, I'm saying the prices will stay the same and the iMac 21.5" models will run cooler.
If you want to continue to speculate on the 27" models, we could see an overclocked version of all of the above to improve the graphics on the base models, with discrete NVidia parts for the 'better' and 'best' but that's very much speculation on my part.