Rosberg looks like the gods are on his side this year whilst Daniel R and V Bottas look to have immediate potential.
I don't really see any outstanding guys in F1 other than those above.
As far as others who are not yet in an F1 seat I just don't have a strong enough crystal ball...who amongst them can get into a winning seat if Hamilton, Rosberg, Daniel R, Seb, Bottas and Alonso are all hanging around for another 2-3 years...
There will be a battle for the second Ferrari and Williams seats (sorry Kimi you're fired and Massa ;unless you get some podiums ahead of Bottas your career is only going one way) but say if Hulk and Danni K get one each the chances for everyone else are very slim.
Its going to have to be a test driver who comes in and P***** all over the team regular to get noticed....so difficult to do with limited testing time...