If Smoak hits his Steamer projections, he should be fine (or at least playable). For whatever it's worth, this career road numbers are almost exactly his Steamer projections, so it's not far fetched (especially when you consider the number of extra games he played in Oakland and Anaheim). If he sucks, we can rotate guys through the DH and probably get similar production. Really not a big deal.
As for A-Rod, he has 10/5 rights. Who knows if he'd even be willing to waive them to be a DH. He might prefer to sit back and tick off the Yankees lol. If he was willing to, and the Yankees paid all but like 1M, maybe.
edited: Oh god, I'm agreeing with TwistedLogic...