Happ the player is fine, he's essentially who he has always been and for that production his contract is very reasonable.
Having said that, resigning Tucker probably puts you in a spot where Suzuki or Happ has to go if you want any cash left over to make meaningful improvements in other spots, and that's before considering a big money pitcher like Eovaldi coming in this offseason. A $45m CBA number puts you at $55m under the luxury tax...with only 9 players signed. Steele is making $6.5m this year and I don't think that number can go down, so there's 15 spots left for arbitration costs, piecing back together a bullpen (Pressly, Brasier, Thielbar, and Keller are all FAs), and adding at least one high quality starter, if not two.
We'll see where the events of the next few weeks leave the farm system, but going from Suzuki or Happ to Caissie is probably the least painful way to find what is going to be a needed $20m.