There are plenty of examples of that happening- Ibrahimovic, Podolski, Shaqiri, XhakaI can't say I see it like that personally.
People move around the planet all the time and change their citizenship. If people find a new home and change their citizenship and decide they want to represent it, I have no problem with them doing so at all, I'd be all for it.
Pretty sure I will be in the minority here mind.
I think in the British Isles it's fairly common that people have ancestors/antecedents from other countries within the British Isles. Growing up, I was certainly aware that the different parts of the family were from or had come from Scotland and Ireland, and even Wales. To the extent that I'd never experienced any animosity between British nationalities, in terms of who to support in sporting events, until I went to university and found that my Welsh housemate hated England.

