I don't expect Ichiro, Jeter, Tex or Granderson to suddenly fall off the cliff. They could but I think Jeter and Ichiro have been written off before. "Rivera simply replaces Soriano" is a silly statement. Say it out loud. Martin didn't hit his weight last year. Cervelli can do the same. As for Pineda, I guess it depends on which report you read and who you believe. He was projected for June, he said ST. We'll see.
Nonetheless, being 5 months older isn't the death knell for the Yanks. The parts lost, excluding Swisher, doesn't add up to much.