What you can know for sure is that it will increase costs and cause disruption. You can know for sure there will be fewer employees at a higher minimum wage. This will come as a result of all of these: fewer Big Macs sold at a higher price point, fewer Franchise locations over time, and greater automation in existing restaurants.
You can bet McDonalds knows the unit cost for every thing they sell. Labor to the penny. So are you one of those “10 dollar hamburger if minimum wage doubles” people. If so you are being ridiculous.