Let's assume all of them are making minimum wage, so $15 per hour would basically double it (the average wage is almost definitely higher than $7.50 considering minimum wage in some area).
Now the average profit per year for a McDonalds owner is $1.25 million per year. You think the activity is going to cease?
Of course it may make automation about $500k more appealing, but automation was happening one way or another.