Costa and Nandos are not the end point of gentrification. A Laura Ashley and an M&S would be a bit closer.I'd much rather a high street of Best Kebabs, Chick Kings, Body Music (the record shop at Seven Sisters) and West Indian fruit and veg shops, than crap like Costas and Nandos.
Gentrification is good in some ways, but it needs to retain independents, not become identikit.
If course, properly gentrified areas have more than their fair share of independent retailers, but they're not ones you'd recognise from any high street around Tottenham.