It will fly again, you don't just throw away airplanes that are not ready to retire yet. It may be refused by many countries (as an excuse for protectionism, or they don't have a lot of pilots that are good enough to fly them), and they may get multiple redundant failsafe to ground any unusual issue no matter how small.
I would expect them to be put into shorter domestic only routes (no need to worry about foreign countries grounding them), not loaded up to the max, maybe reducing the capacity to increase extra safety margin. It may not be as profitable of a plane to fly as before, and Boeing will compensate the cost difference for that.
Or Boeing will pay for extra training so only astronaut grade pilots will fly them, and therefore only fly them at a premium pay.