My suspicion is that Microsoft will do exactly that: they will pull the money, sabotage the partnership deal and focus on rebuilding GPT in-house (with some of the key OpenAI people hired away). They will do this gradually, on their own timetable, so that it does not disrupt the GPT Azure access to their own customers.
I doubt that there could be a replacement for the Microsoft deal, because who would want to go through this again? OpenAI might be able to raise a billion or two from the hard core AI Safety enthusiasts, but they won't be able to raise $10s of Billions needed to run the next cycle of scaling.