Of all the battle system changes that are coming, this one worries me the least. MP cost has always been percentile to max MP. Apply those same figures with 10k max MP in mind and done deal. PIE will likely factor in the same as well. They will use a formula to figure out what percentage of MP players can add at any particular level, and add that number plus some change to match the additional MP it gives you over the course of the average time of various duty clears. The quicker MP generation should also be advantageous should you be KO'd and raised in battle. At least on paper.