We would not have got an AV referendum.
This I would actually consider a failure on Clegg's part. Not because he lost the referendum, but because he chose to go ahead with a referendum that was basically "Do you want to keep this massively shit system we already have or would you rather have this slightly different, slightly less massively shit one that would make hardly any difference?"
Regardless of the outcome, it was essentially a move to make real, effective electoral reform a near impossibility for years to come. If yes, well, we got our precious reform, didn't we? You want a proportional system? No, fuck off, we only just changed it. If no, well, obviously everybody loves first past the post - no need to change it.
I get the sense that Clegg recognised how miserable a compromise AV was - using those words - and was just overly keen to make even the slightest step towards a fairer voting system. But he fucked up. The definition of "one step forward, two steps back."
Edit: I agree with the rest of your post.