They're about to draft their new Franchise QB so trying to deal Dalton isn't really a big deal, though they might not find a taker with his 17m salary. He's ok, but I wouldn't pay him 17 million and I wouldn't trade anything for the right to pay him that for 1 year and then have to pay him more or let him walk. They probably want him off their books more than anything.
Given there's no dead cap in Dalton's contract, the typical resolution to such conundrums is to release the player after attempts to trade him are unsuccessful.
However, you never know what one of 32 teams is willing to do. After Flacco was traded to Denver for a 4th. round pick, they wrote him a $17 mil signing bonus check to defer the cap hit along with a $1.5 mil salary. That's they're all in cost if they cut him. If they keep him for 2020 that's another $20 mil out of pocket.
Would you rather have the version of Flacco going into 2019 or the 2020 version of Dalton? As far as I'm concerned you (or Denver or whoever) could flip a coin. Or better yet, put the coin in your pocket and walk away.
For the record, I could care less what happens to Flacco or Dalton. It's interesting only in understanding examples of how the league chooses to spend its money.