I think another likely inclusion would be IPTV, this really would make it a central media hub and be the ONLY thing needed to connect to your TV.
DVD/Blu-ray player - elminated with Netflix
Set-top box/Tivo - eliminated with IPTV
They'll also more than likely get the Zune marketplace on Live so you can download songs and play them straight on you home theatre, which I think is more convenient than downloading on PC and then syncing with an Ipod and then putting the Ipod in a dockstation connected to your home theatre.
I think more RAM would reap more benefits too moreso than GPU/CPU as the high res displacement/normal maps are getting massive.