Not quite. Without the other cultures being willing to,adopt British culture, it is almost inevitable that Britain will disappear and, without the other cultures integrating but keeping to themselves, blood will be shed.
Britain is heading towards the same sort of chaos and blood wars that every other non-western nation tends to experience regularly.
Modern British culture is about:
1. No religion
2. lots of shopping -- worshipping at the mall on Sunday
3. binge drinking on weekends
4. lots of random sex, starting from when you are 13 or even younger (yes)
5. acceptance of every liberal cause, from gay marriage or whatever
6. championing the welfare state, NHS, etc
7. football (soccer)
8. Making fun of the French (if you're English) or the English (if you're Scottish)
Sadly, all of what Britain great is gone and it had nothing to do with immigrants.
Currently British culture = gay-welfareState-sex-booze-liberal culture.
Britain as you or I know it is gone.
you mean like WWI or WWII? :)