Not true at all considering free movement of people will absolutely not be allowed. Thaats means however minor the end result is it will not be as easy to travel to Europe as it once was.Well your ability to travel wont change
Even a US ESTA costs some money, requires a more awkward queue to be part of and only allows you in 3 out of 24 months. That's a relatively simple process so I have no how you can assert it will be still as easy.