So there has been some news coming out of late.
1. The sox plan to stay under the first threshold for 2020
2. The sox plan to negotiate an extension with Mookie Betts
3. The sox plan to negotiate an extension with Rafael Devers
For the first one, this would be tricky. If the plan is to keep Betts, then you'd have to deal off JDM (or hope he opts out). That lineup is far less deadly without JDM and if you want anything great in return (top 100 prospects, plug and play big leaguer), you would probably have to eat some money. Then the question is, how competitive would the team be? The Yanks and Rays are deep and still rising in the division. The sox will be limited by their cap number and their aging and fragile rotation. Henry is all about timing, and I bet he sees the timing as poor for the sox to contend next year.
For the second one, I think this is a ploy for PR. Mookie said he is gonna go to FA. The sox are going to make the RSN aware they are gonna do everything they can to re-sign him..... right before he is dealt.
For the third one, if the sox are able to extend, it would probably be akin to the Bregman deal where they don't touch the pre-arb season next year and the extension kicks in afterwards for lux tax purposes