Seattle will identify a handful of players in round 1 that they love and target them regardless of position. By JS's own admission, this is what they did last year. After the 3rd round or so, I expect this draft to be like any other, Seattle will grab bag all the players they feel could be hidden gems in their system.
The term "needs" get thrown around too much. Don't fall into that trap. Drafting a DT is not do or die. Both Branch and Jones were above average this season in their respective roles. We can do better, but it's not make or break. And if we did want to do better, the draft isn't the place to do it. Having watched most of the DTs with 1st round potential this year, I strongly feel that this is a really bad year to take one early. Very over-rated class. Free Agency could have potential though, especially if Melton or Starks become available.
We don't "need" shit. KC has needs. KC would be insane to not draft a QB #1. AZ has needs. AZ would be insane to not draft a QB or OL in the 1st round. You can't say that about the Seahawks. Are there areas of opportunity? Sure. Identify players who will be future stars in your system and go get them.
Long story short, the focus of this draft should not be about filling position X. It should be about finding special players.