Nunez had a player option. He exercised it and the Sox had no choice in the matter.
Pedroia is going nowhere. And this isn’t going to change no matter how many unthankful fans throw pennies into water fountains wishing he would retire.
Porcello, Moreland, Nunez, and Sandoval’s contract are likely gone, and barring a massive turnaround, Thornburg will go, too. Holt and Leon might be retained since they fill needs and work cheaply. Bradley probably stays, too, mostly because trade interest in him was pretty weak this past off-season and he has yet to do anything to make any team reconsider. There was a time when Edwin Encarnacion and Yasiel Puig were in play for Bradley, but those are the best offers I ever heard. (And the Sox were wise to pass on Puig in particular, as he’s just as streaky offensively but also brings worse outfield defense and a slew of alleged attitude problems.)
If the Sox hope to retain Betts, there won’t be much room to bring most free agents back or bring in any high-priced talent...