I agree it is too late.
You only have to go round some of the inner city suburbs of Birmingham (and many other cities I guess) to see the schools where 100% of the kids are Asian (or Asian/Black/Chinese etc).
You only have to go into some of the inner city areas of Birmingham to think you are driving through Calcutta when you see the rubbish, the squaler, the ramshackle house extensions, the rubbish in the gardens, the rats, the untaxed cars, the women in their burkas. It would make you cry.
There are immigrant inner city areas where unemployment is at 20% or more amongst some ethnic groups (how many work in restaurants and similar I wonder).
Many immigrant inner city areas have a huge number of people who cant speak English, have no skills or qualifications, and are unemployable.
Labour (mainly) and Tories (partly) have ruined much of this country and it will never recover.
We will have to live with our "mistake" for the rest of our lives.