I love THT more than anyone, but no one wants him for the purposes of winning.
I think he has shown enough this year that you want him to opt in. Maybe try to get him to work with staff in the off-season on some things. His spot up shot becomes respectable and you fix his foot-work/finishing on his drives and you have a really interesting player.
There's no way the Jazz traded for THT with the thought that he would be some amazing addition in year 1. I'm sure they viewed him as a multi year development project. If he still sucks next year and you are really trying to win, you don't play him and he becomes a nice salary matcher in trades.
I highly doubt the Jazz are going to use all their available cap space this upcoming off season. I'm guessing they try to nab one of the 2nd tier guys like a Kuzma/Grant then sign 1 or 2 playera to short term deals. The cap that THT is taking up will not be missed.