I was thinking of the Yankees as a landing spot for a Contreras trade but I don't think they have the prospects that the Brewers would be looking for in a Contreras trade.
I looked at the Rays and while the obvious trade targets here would be one of their top catching prospects I think the Brewers don't target one of their catchers and instead go quantity over value somewhat here.
Rays: Contreras
Brewers: Ty Johnson (RHP), Slater de Brun (OF) and Anderson Brito (RHP) or Santiago Suarez (RHP).
You may think this is a light trade for Contreras as the Rays wouldn't be giving up any of their top 10 prospects but this is a solid trade. While none of these players are in the Rays top 10 or in the top 100 prospects in baseball they are players the Brewers have targeted in the past. Ty Johnson's scouting report reads very similar to this Jacob Misiorowski guy. Slater de Brun is someone the Brewers were connected with when he was drafted very similar to Sal Frelick but far more physical. Anderson Brito is a very advanced pitcher for his age but similar to Peralta is on the small side and may need TJ surgery but is expected back soon from his forearm strain. Brito hasn't pitched since March. If you don't like Brito then Santiago Suarez is another good pitcher though he is more of a control pitcher than Brito. Suarez has a 1.3 BB/9 which is just insane. Though he doesn't get the strikeout much and he does tend to give up HR's at a career 1.0 currently sitting at 1.8 this year at AA. He has a mid 90's fastball that can touch 97. He would make for a very good #4 or #5 starter. You wouldn't have to worry about him walking batters but you would need an elite level defense behind him which for the Brewers is something they have.
I don't believe the Brewers will trade Contreras this off season and will instead just go year to year with him.