The only teams that likely could give Skubal a $400-500M contract if they want to are the Mets, Yankees, Blue Jays and Dodgers.
Yankees/Mets have the money to spend big and likely will be wanting to add an elite arm. Blue Jays have shown they're willing to fork out monster deals for the right players in previous offseason's - Ohtani, Soto, Tucker - and Skubal definitely is in that group. Dodgers rotation is already crowded and likely would have to trade some arms, but never count them out.
I don't see any other teams getting involved with Skubal at those years and dollar figures. Phillies resigned Luzardo, so don't seem them at all being a dark horse anymore.
Also, will be interesting if the Pirates entertain trading Skenes next offseason.