Yes, I do think that Seals will also provide rewards, in addition to giving members access to dungeons.
Here's how I see it happening.
  • Do 5 missions to get 10 Seals.
  • After mission 5, Dungeon is accessible.
  • Cost to enter, 3 Seals.
  • Item cost 5 Seals
Meaning you have to pick and choose what to spend your Seals on.