I just hope we don't reach for a 4th round player or draft a specialist that doesn't make sense (Jesse Williams).
I'd be totally fine with drafting almost any position at #56 if it's a great player. For example, if by some fluke RB Giovanni Bernard is there, I'd be fine with getting him- his game reminds me a little of Doug Martin. I'd love WR Ryan Swope at #56 too. Basically, if it's a great player, I'm fine with finding an all-around DT a little later on. There are some options in that regard throughout the draft, such as Abry Jones from Georgia in the late rounds.
My guess is that if there isn't a value pick at defensive tackle, we'll probably see them draft tight end, offensive tackle, or corner at #56. There is expected to be very good value at those positions in the late 2nd, and Seattle is known to be looking at all three of those spots. I'd love to see Zach Ertz make it that far. I'd been hoping for Menelik Watson, but newer reports say that he's a solid 1st rounder and teams were not scared by his combine flop.