How long will these old buildings last?

I've been meaning to blip this wee telephone exchange for a while now. It epitomises the look of a late 1960s, early 1970s building found all over the UK. You could find them as telephone exchanges; social security offices and tax offices.

These buildings are starting to show their age and my gut feeling is that they won't be around for much longer.

I need to snap a few more before they are all gone :)