I'm not really bothered by SAM as either DPS or Tank. However, the expac will probably bring 2-3 new Jobs and it is unlikely that more than one will be a dps. With that as the case it means that if Red Mage, which has been strongly hinted at, comes out it and SAM is dps, Red Mage won't be a dps.

While I would be fine as SAM as a DPS, if I had to pick one class from the prospective new Jobs that have been hinted at to be a DPS, I don't think I would pick SAM. That said, I also think I'd probably prefer something a bit different for the next tanking class and SAM would have the benefit as DPS as being able to share a gear category with DRG.