Just for point of discussion since since you only mention living in the UK for over 5 years but if someone had resident for 6 years or over then they could apply to become a UK citizen. For most nationalities (but not US I seem to remember) you could become a joint citizen so wouldn't really have to give anything up in the process.
If becoming a UK citizen is not something someone aspires to then surely a point could be made that that person is not invested in the future of the UK.
If you've only been here for 5 years and want(ed) to become a citizen in the future then you have my sympathies.
For disclosure, I'm British, pro-immigration and voted to remain in the EU; I feel sad today.