They will have to spend their way out of it.
I think they already have obscene commitments for next year: Price ($32M), Sale ($30M), Bogaerts ($20M), JD Martinez ($23.75M, if he opts in), Pedroia ($13M, ouch), Rusney Castillo ($14.75M, anybody seen him lately?), Eovaldi ($17M). In fact, it looks like Vasquez is the only other guy under contract ($4M), and they've well short of a team. Lots of pre-arb and arb guys. Betts will cost them a fortune. They've already got $159+ in commitments. If Sale and Eovaldi are truly injured, Pedroia is washed up, and Castillo is still doing his disappearing act,, they are well and truly fucked. Baseball-reference estimates their payroll at $224M, $223M, and $238M for the next three years. Imagine what happens when they have to pay Devers.