[ouEight12]

Honestly, I know this answer isnt going to be that popular in some circles, but.. yes. leave it. If it offends your sensibility so much that you just can't be 'caretaker' for this mess, walk away.

But if it's "working fine and generating heaps of cash" as far as upstairs is concerned, there is no way you play the 'refactor/redesign/replace' game and come out ahead.