Well it does not depend on design as much as it does mechanics of the engine. Granted, design is indeed an issue but even the much less detailed games than CrySis had issues getting above 26 FPS. It is the fact that it is rendered by a DX 10 compatible hardware engine.

There is hope. This is part of interview with Cevat Yerli, CryTek employee:

Eurogamer: There's a lot of hype about the visuals in Crysis. But what if you don't have Direct X10?

Cevat Yerli: As a PC game developer you have to make sure your game runs on two to three year old PCs. In fact, the current specification we're planning for is even four year old PCs.

If you're a gamer who bought a new gaming PC two or three years ago, you can play Crysis, and you will get visuals that will compete with visuals of that time. Of course you won't get the super Direct X10 graphics, but we are competitive.

Full interview available here.

I hope they aren't full of crap like most companies. I am excited to see the new clothing and armor work ups.