Probably scores this season. If not he has to eventually. He can score 10-15 goals. 20 on a lucky year. It's not like he scores 5 or less. If that was the case nobody would like him. He can be a good 3c. Outside chance for a second center but after this season that's super unlikely now
Sheahan is not a 2C in any way, shape or form, and he'll never score 20 goals. He might score again next year, but the sooner the team moves on from him, the better. He's soft, he doesn't play like he's skilled (in spite of a bare handful of highlights from past seasons), I don't think he's particularly good defensively, and it's not even like this year is really a huge aberration: he's been trending downward every single year he's been in the NHL, and he's at an age where every season should've been building on previous seasons in at least
some way.
*shrug* Trade him if he has any value, but I don't think he'll ever be an even mediocre player again. If nothing else, the team would be improved solely by him not even getting the minute or so of PP time he gets per game, and it would be dramatically improved by him never again appearing in OT.
All that said, I'd be really interested to know if any other player has ever rebounded from such an utterly horrific season to have a decent one after. I can't find any evidence that's either not injury-related, or that's just a great player who had a down year, but maybe I'm missing someone or not thinking of something.