I don't think it's a given at all (that he'll be off after this season). His game is developing quite nicely here, and he's well-served to stay until someone truly massive comes calling. Otherwise, he risks getting buried like he was with Chelski.
Even if his agent can't see that, Rom can. And he's too smart/wise from past experience to be led astray.
If Martinez goes, I think he'll go. Don't see him staying here through a transition period, that wouldn't make much sense.