One thing the USA seems to be missing lately is non-goalie prospects of the "franchise player" type: Kovalchuk, Heatley, Ovechkin, Spezza, Bouwmeester, Gaborik, Malkin, Nash, etc. Kessel could be that type of player in a few years, but other guys like Crosby, Brule, Vasyunov, etc. will also be coming during that time period.
The safe money is on Canada staying near the top due to their great depth and top line talent at all positions, with Russia staying close provided they can develop some consistently strong goaltending. The USA will continue to put together solid teams, but ones lacking in that extra-special star power that some of the others can provide. The USA seems very good lately at producing a lot of depth though.
Personally, I can really see Finland emerging as one of the dominant hockey powers by about 2010 or so, going on a run of impressive results like 1998-2001 Czech Republic and 2002-2004 Canada.