Changing tastes and a unwillingness of a younger generation to follow in father’s footsteps running a restaurant.
It’s the same with Manchester’s “Curry Mile”. In it’s heyday, there were probably about 40 South Asian restaurants along the half mile strip of Wilmslow Road (it was never a mile). Now, there’s may be a dozen left. But, as each one closes, another opens but now it’ll be Middle Eastern restaurants or shisha bars.
Two separate things, customer demand vs owners’ kids not wanting to continue the restaurant.
I think most immigrants want their kids to do better than they did – restaurants were often the only viable path for many (also cab driving in the US). It’s a hard life. Likely a better outcome for the next generation to be able to do other things. It’s the reason many inexpensive and mid-level “Indian” restaurants in the nyc area have all converted to Bangladeshi in the past decade or more – they are the newer immigrants; Indians who emigrated long enough before that (and populated little India, curry row, and jackson heights) don’t want their kids in that hard life. And so it will go with recent-immigrant Bangladeshis as they settle, educate their kids, and equip them for a better life.
The demand side is also interesting, in terms of what appeals to the younger set of consumers. My friends’ kids in the US veer towards East Asian and Mexican / Latin American trendy over anything South Asian or Middle Eastern. irrespective of their personal origins. Or burgers. And boba, heaven help us all 
Interestingly about the Bangladeshis. Traditonally, since the 1970s, almost all of the UK’s “Indian” restaurants have been owned by Bangladeshis - with almost all of them coming from the Sylhet province.
In my part of England, many of the recent openings have been by Indians, often wanting to offer more traditonal regional food. They’re finding that the changing tastes of Anglos now makes this good business.
By the by, in my part of northwest England, most taxi drivers seem to be South Asian immigrants. Of course, it’s a good first job for new arrivals with a limited command of English.
