I remember The Plaza, @Needmorelego. Oxford Street could be packed but The Plaza was like a ghost town! I don’t remember the food court, only the one (that is still there) at West 1 (in Bond Street station) and The Place to Eat food court at John Lewis.
The Oxford Street area has pretty much every fast food chain and lots of mid range independent and chain restaurants, they are just on the streets that lead off Oxford Street.
The west end of Oxford Street was always much better than the east end beyond Topshop. The loss of the department stores, the second Primark and the redevelopment around Tottenham Court Road changed it to be the other way round, just as The Plaza closed. I’ve noticed recently that there are a lot of new stores opening on the west side and far less money laundering American sweet shops. If the article OP posted is right, it’s going to be a huge blow to the regeneration. I have high hopes for the long delayed opening of Ikea!
Online shopping has killed the high street. Oxford Street is going to have to reinvent itself as a destination with shops. You don’t go to places like Covent Garden or Coal Drops Yard purely for the shopping, you go for the experience and ambience.