The idea is admirable but I think it may end up being something that is better in theory than in practice. If fighters don't want to pay the extra, they will drop out of the rankings and more poor mandatories might be called when all the big names are taking another route. It's a problem I see with the IBF when they try and make final eliminators. A lot of fighters believe they are worth more than 50% purse against who the final eliminator is called against, and if they win they believe they are worth more than the 25% against the champ, then you end up dropping down the list and vacant titles are contested between the first two to accpet (Glazkov v Martin for example), same with final eliminators (Jo Jo Dan v Bizier), and often to fans without knowledge of how it works, the champion will take the blame for a sub par opponent or the sanctioning body for sticking to their rules.