The main thing is that Jorge will officially be the DH of the Yankees. He can still hit and has a lot of power left in him though.
As for Martin, his last two years were terrible, but he is young and might bounce back surrounded by talent. Also, speedy catchers are a rarity in this league and hopefully he'll be able to swipe some this year.
Martin isn't a good defensive catcher, but he is still so young and can be improved. He'll probably bat in the lower half of the line-up and IMO should do better.
I do not think that he is the next NYY permanent catcher. They'll just have to make due with Martin/Posada/Cervelli until they find someone more consistent and permanent and his name is Jesus Montero.
I predict that Jesus will take two-three years to be pro-ready and I'm content with Martin during that period.