I think replacing the lead actor in a sitcom would be a bad idea, although it has been done, notably with Arthur Lowe being replaced in Potter, and Leonard Rossiter being replaced in Trippers Day.

I've always thought if you had to replace Father Jack then Wilfrid Brambell would have been a great choice!

Now that I can mention it without giving away spoilers for the quiz , a good idea seems, on paper, what they used to avoid replacing Leonard Rossiter in the Reggie Perrin saga.

"The Legacy of Reginald Perrin" didn't work too well, unfortunately, I understand Geoffrey Palmer was good as the new lead (never seen it myself, yet), but Leonard was missed too much...

Guess the same idea might have worked with a "Legacy of Father Ted", though, Ardal's character seems strong enough to take the lead (in a Frank Spencer way ), with a new assistant, maybe someone completely different, say like Dara O'Briain...

But they all dismissed the idea, which was probably for the best.

However, I've always thought it was the closing down of Father Ted to cause a deterioration in Dermot's health, rather than the other way around...