I'm personally more interested in seeing a change up or at least clarification of the judging system.
More distinct point scoring, like how in boxing it is obvious a knock down = a 10/8 round for example.
Obviously its not as simply as that in mma because of the far wider skill set fighters have at their disposal but I would like to see what constitutes a 10/8 round defined better for example.
As for extra rounds leading to fighters not giving their all, to be fair I think they would be training to go the distance and this would include the potential over time round so by all rights it should be a massive problem and they should be looking to win within the normal timeframe anyway.
I actually think a single round after a fight had been declared a dare would probably lead to a lot more slug fests as both fighters know where they stand and that this round is truly winner takes all (plus both are likely to be gassing and sloppy)
Maybe they could have the final round lasting on 3mins like a boxing round, set it up for the fights to both just go all out for the win in the over time round....sudden death so to speak.