If they raised the minimum wage 10% (not double, let's be realistic), it would raise McDonalds' incentive to eliminate a small percentage of staff.

Look at how supermarkets now have self-checkout. 4 self-checkout stations going with one employee monitoring, and customers don't mind using them. In fact many customers prefer them because they help them get out of the store more quickly. There's no reason to think that McDonalds won't eventually try to eliminate some of the staff that takes orders. It's just a question of when they'll be incentivized enough to try it.