Nobody else can get involved with Princes Quay. It's a privately owned facility, contact the centre manager Tony Wilkes. That'll be fun for you....
Rent and rates for shops/businesses are too high in this country. That's why shops are empty and why manufacturers struggle to compete in the export markets. We should have had a correction as a consequence of the financial crisis in 2008 except 'judgement day' has been repeatedly postponed by Governments trying to maintain high property prices.
Castle Street isn't being pedestrianised, there's a proposed 'land bridge' over the top of it to link the city centre to the marina.
There were plans for an underpass a few years ago, I was asking what happened to them. I'm guessing they were binned then.
A cut n' cover was never really viable. Too expensive and meant a lot of buildings would have had to be demolished.