He definately needs a major outside the OZ open. He has the game to win at wimbledon which he truly wants this year. I expect him to win at least one more major this year. If he does not burn out he might just win the grandslam. He is that good this year.
Neither he nor Nadal has "the game" to win at Wimbledon. Ten years ago they would be both be R1-R3 casaulties.
In todays tennis, not many people know how to play grass court tennis, and the courts are obviously slower. When the grass dwindles away and gets even slower and higher bouncing, they can obviously stand their grand though. I would not be surprised if one (or both) of these guys finds themselves in a big hole early on.
If Nadal changes his grip on his serve again
he will probably be as dangerous as earlier years. Djokovic needs a good draw, but I still don't see him beeting Nadal, Fed, Söderling and Murray. A lot of dark horses like Malisse, Llodra, Karlovic and Lopez will also be difficult IMO.