The Twins have some interesting starting prospects coming up but the thing about pitching prospects is that they tend to disappear overnight.
I'm not going to count my chickens before they're hatched. We see rotation attrition in every baseball season. If those guys are healthy and good, they'll get their shot as the pitchers in front of them are injured and/or ineffective. The Twins couldn't even make it to Opening Day this season without losing their 2017 All-Star starting pitcher.
And if several of those prospects manage to be healthy and good at the same time, that's not really a problem... But counting on that to happen and trading away an established starter before they've proven themselves is a good way to enjoy a season of Andrew Albers at Target Field.
I don't really disagree with anything you said here, but I just think there's a pretty huge difference between guys like Gonsalves, Thorpe, Littell, Romero, Slegers, May, and Mejia in comparison to guys like Walters, Albers, and Deduno.
Now that said, I'd certainly be fine flipping one or more of those guys for an established ML need (such as C or a 1B/DH type), as we have too many of them and more coming behind them. But I can also see why we might flip a guy like Odorizzi to make room for them too. It really comes down to how many open spots the FO is willing to roll with. Right now, our sure things to be in the rotation are Berrios, Gibson, Odorizzi, and most likely Pineda. That's a lot of guys for 1 spot, and I personally struggle with the idea that May and Mejia won't be able to outperform Odorizzi in 2019.