He's a goner when his contract is up unless they make the playoffs. Dombrowski didn't hire him, and Middleton isn't going to interfere with Dombrowski they way he did with the defanged Klentak and the disinterested MacPhail (i's the best thing about having Dombrowski, really). If Middleton felt otherwise they would have already picked up his option, since managing as a lame duck isn't working out too great either!
And really, the coaching staff is solid? The 3B and bench coach are on their way to a fifth losing season under two different managers. The 1B coach, four. The pitching coach is a huge improvement only because they may have had the worst three-year stretch of pitching coaches in MLB. Long is fine but not actually that different than Dillon (geez, I hope Dillon at least got a watch from Harper for the MVP win). Regardless, you don't have to fire all the coaches when you fire the manager - clearly!