Altrincham was on its knees and changed. It’s not difficult to work out what is needed. For those who find it so, just read any of several Reports on Towns (The Manchester Metropolitan University Report being one).
Towns need reconfiguring with smaller shops offering local produce and local service. They need to be easily accessible and largely small and differentiated. Shops need to offer stuff that is either not readily available in a Supermarket or Online OR offer stuff that customers like to browse through before buying (Clothes, Vinyl, etc).
Towns no longer need big and bland. Online, Supermarkets and out of town covers that. They also don’t necessarily need shops supplying goods. Services are just as popular.