The only thing that FH2 "misses" is destroyable or more interactive environment, other than that I see no point in changing.
One could miss also things like 64+ player support (very few engines, if any, support this), component damage (incl. immoblization) to vehicles (very few engines, if any), working sight adjustment for scopes and vehicles (very few engines, if any), unique selectable kits for each map for different classes, running in 64-bit mode so application can use more than 2 or 3 gigs of memory and thus allowing more textures, larger maps, etc., higher ceiling, more realistic FOV (now it's "everything is closer than it looks" in order to make maps appear larger), particle effects that would actually utilize modern GPU's power instead of choking it down with DX8-compliant code, no artificial limits on the number of squads on each side, and, and...
Oh, and CryEngine
does support larger maps (CE2 in 32-bit mode works at least up to 16384 m*16384m, 64-bit mode works with even 65536m*65536m, theoretical limit is actually 262144
kilometers * 262144 kilometers), it just needs a NASA supercomputer to run even 32 players on a 4096m*4096m map using CE2, and hit detection is among the first things that starts to break down.