yeah the thing to remember is that this is a tech demo. where epic are saying "okay we've incorperated these features into our engine for developers to use".
sure, as of right now, hardware tesselation is very expensive, and you need a super rig to run it. similarly with the real-time cloth physics. and that's the thing. it was all realtime. it wasn't a pre-rendered scene.
but back before normal-maps were main stream the exact same thing happened. they tech-demo's normal maps as a real time feature, using a super rig that no regular user would have, but then technology cought up and even a $60 card could run it.
this is the kind of stuff you should expect to see in 3 years time when sony and msoft make their next gen consoles. because by that point, the hardware will have been able to catch up with the software development.
