Is the exchanging of the crown a non-optional event? I couldn't imagine a situation where you would not want the crown (notion thief in play aside..) but just curious. There is currently no way to interact with emblems (right?) , and the way the article from wizards reads there will not be a way for there to no longer be a monarch once the effect begins.
It's definitely an interesting mechanic, and as long as there are cost effective ways to get the effect into play in vintage I expect it to see some play. This, plus library, plus Bob, plus gush is card advantage to the max.