Those same young people will probably cheer just as much when (if) Leicester City win the FA cup (well, I can dream).
I'm of Scottish descent - great-grandparents - yet I still cheer when Scotland win anything major.
I think you also need to be aware, anotheoldgit, that it's the Asian population that's keeping amateur cricket going in Leicester. There's a great big, purpose-built cricket oval on Abbey Park, it and the neighbouring pavilion being put in place when the park was first laid out in 1882. It went largely unused for its original purpose during the nineteen-seventies and eighties. Yet you can go there now any afternoon/evening of the week, and there are people playing. This is not 'family fun', but works,community and neighbourhood sides playing practice games, with matches on the weekend and some evenings. Mostly, the teams are made up of British Asians, but with a fair smattering of British Europeans too. I'm not a cricket fan at, in fact I hate the game, but it's really great to see this bit of the park coming back to life again.
Something else you need to understand is how much Leicester people take Asian culture on board. Whilst there are still, sadly, more than a few racist bigots in the city, the British Asian way of life is very much part of daily life here. And I wouldn't want it any other way.