Somewhere along the line we stopped looking to our own previous generations (which include European nations as, you know, we’re Europeans) for cultural identity and started following Hollywood as our cultural oracle.
Generations of this has lead to the mess you see unraveling in the UK at the moment.
A few Pakistanis moving in down the road doesn't stop British people practicing British culture. The reason they don't can be summarised as laziness and ignorance.
"The pub got turned into a mosque", maybe it did but it wasn't because the Moors invaded fgs. A successful pub gets to carry on being one - if it's not successful, maybe that's because people stopped using it.
And pray tell, how does the influx of a muslim, non-alcohol-drinking population, influence this?
But as far as I can see, they're working for the NHS, running restaurants and shops and so on, and buying/renting homes that come up on the market like everyone else. London's Muslim mayor was elected by an absolute majority even though Muslims are only about 12% of the city's population.
Nobody is stopping Brits from doing Brit stuff - it's our own fault if we choose not to.
Far as I can see, what's done a lot of basic pubs in is a combination of lifestyle changes, people who don't like the smoking ban, and younger people wanting to spend time down the gym instead of drinking.
The UK is large, so maybe either of us are just looking into a small bubble not representative of the whole, but the times I've visited the UK in the past, I didn't see much of what you seem to describe. Perhaps in the very center of London and its shopping malls, but those are not representative of the UK whatsoever.
The decline in Christianity in the UK probably has something to do with it, and that in turn is loosely correlated with WWI and WWII. That's also another historic factor - families destroyed, and fewer families and so on.
And then the elephant in the room - London.
Want a job? Move to London or the south east and leave your family behind. Born in the south east? Want to live in the same street as you parents? No chance. Same town? Unlikely. Do you know your neighbours? Maybe. Do you see them in the church any more, or even when you walk down the street?
Culture is alive and well outside of London, despite its drain on the rest of the UK.
Social, and economic mobility is good, but some of the side effects are only now becoming apparent. Successive short-termist poor governance for decades has been the problem.