Who is going to pay for this? If it's Tesla, then the smart move is to put CCS into cars right now (and as a side benefit, standardize their US and European models.) If it's the customer, then it's an annoying non-trivial cost you'll have to bear. Yuck.
But it doesn't matter. The number of vehicles taken either way is negligible. In the old days, you had to change the miles/km speedometer to the other one when you took you car with you as you emigrated. Buying a charge adapter is easier.
Single phase vs three phase is the big reason for a difference between US and EU charger plugs though. Three phase is pretty uncommon in residential areas in the US but is common in many EU countries. Industrial customers in the US will often have three phase but it's pretty rare to see outside of that.
My bet is that within two years Tesla standardizes on CCS for its US cars (thus getting rid of an annoying upgrade/adapter/retrofit problem) and then what'll be left is the sad minority (AKA me) who are stuck with the dying standard and an annoying dongle.