My DH was a manager at several Woolworths, and got out before they went bust. It was clear that they had lost their niche in the market. Other shops, such as the supermarkets, Wilko, Superdrug, etc, were selling many of the products that people would once have gone straight to Woolies to buy.
During my DH's time, there were a couple of attempts to revamp their image and find a niche. One was "What Debbie wants", with the idea of stocking products which would appeal to their typical customer - the imaginary Debbie, a young working mum with 2 kids. Evidently Debbie didn't want what Woolies was offering, as profits kept declining. Then they decided to go for the niche market of party supplies. That didn't work either.
It became obvious that their days were numbered. When my DH got the chance to get another job, he took it, and others were doing the same. Woolies just lost its place in the market. Too many others had encroached on its turf.
I think everyone misses the pick'n'mix, though.