I’m guessing that “excessive capacity” of healthcare services means simply ‘too much healthcare’. Which is a concept that only a socialist could come up, and which should scare the crap out of any rational thinking person.
Indeed. It will not only have the effect of diffusing complaints about the NHS ("You're tired of waiting for your operation? Go to Romania...they can get you in next week") but may increase some cultural hostilities. If you are French or Italian, will you be pleased about the fact that you may experience greater wait times for healthcare services now as a result of a huge influx of patients into your healthcare systems?