I agree that Baez is probably the most likely of the three to be resigned. The rumors were that the Mets were the only team with a lot of interest in him, and they might not want him for a multi year deal. I wouldn't object to them signing him for a multi year contract, if the AAV was somewhere below 20 million per year.
Regardless, I hope they sign one long term offensive player to act as an anchor, and spend whatever is left over for the best starting pitcher they can get. I think they have enough offensive potential in the minors, so depending upon how they progress, strengthen the starting staff each year. Rinse and repeat.
I hope they also resign Contreras next summer, if they can fit it into their budget. If not, trade him at the deadline.
Brennen Davis might be with the team next year. At the very least, they should have a much better idea of whether or not he can be an impact player. With the exception of shortstop, they seem to be adequate in the infield, until a better player comes along. I'm sure that Happ will be in left field next year, for better or worse, and if Hoerner is moved to center, their outfield will also be set, until an opportunistic improvement is made, so the starting staff is the place to put their money.
If PCA turns out to be as good and as ready as some seem to think, that might put Happ on the market right around the trade deadline. If he is on one of his hot streaks, he could bring back a pretty good haul. Maybe the Reds would like a home town product that hits well in their park.