It can be done, but it's going to require a bigger change in attitudes on all sides. One man in Ireland started it up here, and now it's worked it's way to the UK.
One of the big advantages of cycling in heavy stationary/slow moving traffic, is the ability to pass most of it. The freedom to do that shouldn't be taken away, nor should we be made use only off-road routes. But a fixed distance needs to be given.
I've said if a vehicle passes me, and I can touch it "it's too close". That's 30 inch at the furthest possible (Outstretched arm), I checked after posting.