I doubt there will be any major changes in the tourist areas. Too difficult to enforce. Cozumel is almost a USD economy in most areas of San Migel.
I almost always have pesos that I use as a reserve and to purchase off the street items (cokes, ice creme, etc.) It's easy to get a fair exchange rate from the bank so I may just start carrying more. I don't like credit cards either so I will probably buy less while in MX.