The majors fly on Europe and are already capable of doing what is needed as that rule has been in effect over there for a number of years now.
Most of our travel is between the US and Belgium. I log in using an account keyed to my Belgian destination address to find the actual prices, they log in using a US based account so I can pay for them. (Yes, you can stuff up the system by booking tickets in Euro and paying for them with a $US credit card...)