All heavy traffic is a problem, I didn't intend to exclude any kind of transport. I imagine that cyclists would be happier with fewer cars, and lorry drivers would be happier with fewer everything.
Proposed solutions to traffic problems will no doubt continue to crop up, and some of them will be adopted. Whether this one will remains to be seen, but I'm not holding my breath. The real solution to congested cities is much better public transport, but that isn't likely to be a short or even medium term possibility - billions of pounds of investment would be needed.