Very salient points all the way around!
My only disagreement is your comment on 2-3yrs before he steps to the forefront.
He has learned and made adjustments at every level he has been at. Yes, there have been hiccups, and the BB for a time last season was alarming. But what did he do yet again? He made adjustments and found himself. I often find it amusing when a pitching prospect reaches the ML level, like Berrios as an example, and struggles initially, and some claim he's automatically a bust of some sort. I think Gonsalves will be up in 2019, will improve, and could be a fixture by 2020.
That being said, I honestly think Thorpe is an even better option. Here's hoping both are part of the 2020 roation.
I'm not giving up on Gonsalves yet and I think he'll improve in 2019, but the question is how much? He just doesn't seem to have the stuff. The Twins have other options so if he's valued as a throw in for a trade no big loss. I agree Thorpe is probably a much better lefty option who is getting close. Certainly has much better stuff.