Would viewers have still tuned in?

Probably, her ratings went down after she married.

Maybe but the real mistake was breaking up Rhoda and Joe for good.

If they'd had a will they/won't they get back in later seasons would have

been great.

They should have moved a little slower with Rhoda and Joe's relationship. It would have been fun to see Joe pursue Rhoda for a couple of seasons. They started with the wedding and then everything went downhill from there. The wedding should have been the final episode.