Conversely I don’t see how they can’t be returned to the sky. Boeing has deep pockets and the US government will push behind the scenes to make sure it happens, regardless of whatever public statements they make. There is no way regulators will be able to keep this plane grounded simply on the ground of politics.

You're saying we literally can't stop our representatives/"regulators" from getting us killed anymore. Lovely.

Both accidents could have been avoided if the pilots knew about the changes in handling and in MCAS and how to handle it. So this is not the kind of flaw that would make a plane uncertifiable or unflyable. Combine that with Boeing’s strong lobbying efforts and importance to the US economy, it is a certainty the planes will fly.

The simple solution would be to just remove MCAS and take the certification as a new plane. Boeing might have to eat the retraining costs but it's got to be better than eating the cost of the planes should they be deemed unfit for purpose and Boeing sued by every airline to recoup the costs of the now useless planes.

There's also the possible hardware fix to add an additional AoA sensor and change the software to limit the total deflection allowed + add a way to disable the MCAS only while keeping the electronic trim. The plane itself isn't irredeemable by a long shot though.