Seems rather short sighted in my opinion given that the current scientific consensus is that Covid will become a seasonal thing as it mutates which means that booster shots will probably be needed. Given that amount of R&D funds that the two companies have put in I would imagine they would be reluctant to join in efforts to produce a vaccination for future variations.
They're simply betting on mRNA only, so AstraZeneca and J&J won't be needed anymore.