what I mean by that hardware point I made is that Crysis was developed at a time where PC hardware was getting faster and faster in clock speeds, and Crysis was developed with the idea in mind that as CPUs get faster and faster clock rates, the game will run better and better.
but right at the time the game came out, the industry shifted from pushing clock speeds to going more and more multi-core and multithreaded.
Cryengine 2 was not made with that in mind, and so on today's hardware, which basically usually still runs at the same speeds as the CPUs did back when the game released, the game still has performance issues.
today's consoles have way better CPUs than those the game was originally designed for, but they work completely differently, so a more modern approach is needed to port them, and at the same time this new engine will massively boost performance on PC as well.