Javier Hernandez faces playing for Mexico in the Gold Cup (starting today) and then the Copa America from 1st of July before starting the new season with Man Utd. Mexico are one of, if not the favourite for the Gold Cup and so are likely to progress far with Hernandez starting regularly and so having to play a lot of games. Mexico will also be expected to progress quite far at the Copa America probably being amongst the favousites again and so Hernandez will again likely play a lot of games. This will all be great experience for Hernandez and I expect him to shine however there is the risk that he could burn out next season, I'm not sure whether he'll have any sort of break before the new season with Man Utd?
I think if anything the Gold Cup will help him. He was struggling a bit against top class defences like Barca and Chelsea in the latter part of the season, so the chance to rip Costa Rica, Cuba and El Salvador to shreds should get his confidence back up. He'd be at more risk of burn out if he had the frustrating Barca game as his last game of a long season, or if he was playing against some of the best defences in the world in the WC. Read the signature Kamran, read the signature...
We will have Rooney,Berba (if he stays), Owen, Welbeck, Diouf, Machdea, which is adequate enough cover.
I don't think he'll burn out. He doesn't play every week and is picked when he's sharp. Will no doubt continue to score crucial goals next year, as he did this.