In my Dutch office, out of 15 or so employees, one is Romanian, one is Greek, one is Iraqi (speaks Arabic, English, Dutch and Japanese) and the others make weekly trips to Belgium, France, Spain, occasional quickies down to Italy, Prague, Stockholm, etc. They have a München affiliate with three people. One is from Holland, one is half Bavarian, half Hungarian, and one is Bulgarian. The number of people who speak only one language? Zero. To them, it's like a company with their HQ in Dallas, with people from other states from Washington State to Massachusetts. There are others being from Australia, Brazil, Mexico, Panama, South Africa, Germany.
Except for Germany tightening the entry poionts during the holiday due to (unfortunately justified) fears of "visitors" who scout out Christmas markets to either blow up or drive trucks into, the near total lack of border controls in the Schengen area make traveling Europes borders about as exciting as seeing a sign saying "Now entering Oklahoma." Before the invasion of the Ukraine, even running into Russians all over the place was no big deal any more.
The languages and different cultures will be with us for another five centuries. If it weren't for that, Europe--or at least the western part--would already be having youth seminars about where to have the capital city of the USE.