Wouldn't the idea be to dump Berrios to free up money to sign a better starter, like Bassitt?
ie, if Bassitt is going to cost 1 year $15M (or say 2 years/$26M), then you could trade Berrios + $7M AAV (and maybe a middling prospect) for a lottery ticket and theoretically improve the team (if you believe Bassitt is a clear upgrade over Berrios).
I'm not sure Semien is a good fit for the Jays. He's more of a last resort to replace Bo. I don't want to have to pay him and have to fill a rotation spot.
The Semien/Nimmo trade is interesting. Both have been great players, but both are declining. Nimmo is more likely to be productive for a couple more years, but he's also on a longer and more expensive deal. You might see a deadcat bounce from both, or neither. It will be interesting to see it play out.