Betts, like all the other mercenaries in baseball, will test FA. There is no doubt of that. Trade him during the winter when his return value will be higher than at the trade deadline.
If, and it's a big IF, Sale and Price can come back healthy next season and stay healthy and they do acquire Cole, that would be a top starting staff. The SOX would definitely be competitive even w/o Betts and JD.
I've got no problem with the SOX trading Betts and JD, if the money saved allows them to go after a front line starter. As we all found out this year, offense with little pitching puts the SOX where they are right now.
Btw, someone will have to replace Porcello and it might be beneficial to obtain someone better.
Besides the players the SOX can't get rid of (Sale, Price, and EO), I believe the SOX will definitely keep X-man, Devers, Beni, VAZ, Barnes, D-hern and Workman. It's a crapshoot concerning the others.