There are a couple of FAA equivalents who are more than big enough to hold out. The Russians and Chinese come to mind. The EU will take a lot of convincing too, especially as there are probably tariff issues involved in the politics of it all. And whilst it could be argued that politics should play no part in this, I'd expect that they are very hard to separate....
Questions that don't seem to have answers forthcoming:
1. What is MCAS really for? The story has been that it's to make the aircraft feel the same as previous 737s. If that's the case, then you could simply remove MCAS entirely, and fly the aircraft on a different endorsement. There is a cost to that of course, but it pales into insignificance compared to what this entire saga has cost.
2. Can the aircraft be certified at all without MCAS? If it can't, then is the aircraft actually certifiable at all?
3. Has the manual trim, as fitted to the NG onwards, been properly certified, or was it simply grandfathered? Is this system, as fitted, certifiable?
4. Why isn't there a separate, backup, electric trim system, as fitted to just about everything else?