I don't need to get the Guilds interested in a replacement. I could appeal to the citizens.
And what do the citizens want?
They want the "back in my day" that they keep talking about. They want what they had before all this Patrician nonsense, which was, of course, of the Patricians - they just want stability.
But since they don't even know what they're looking for, they would be easy to convince that what they really want is a King.