Apparently the problem is even worse than I’d realized, and has reached a critical stage. If I read the American laser proposal correctly (which isn’t guaranteed), it would work best on larger pieces of debris. The Italian version will only work on large pieces. If either one is going to be used, it needs to be done now, before the stuff starts colliding and getting ever-smaller. The Japanese proposal is the only one that looks like it might work on smaller pieces, and large groups of them; it also appears to be the most viable technologically, as it doesn’t require problematic high-powered lasers or poorly-tested AI and robotics.
In any case, I doubt this will be a problem in the long term. Someone is going to find a viable solution, and there’s enough money sunk into satellites that it’ll get funded. It’s just a question of how soon — and what the cost will be, as the longer it’s delayed, the more and smaller pieces of junk there will be.
(I just re-read Battlefield Earth, which includes a minor bit where a spacecraft goes into orbit to snatch pieces of debris floating there. Unfortunately the type of motor the craft uses is entirely fictional at this point, so it doesn’t offer any viable ideas for a solution.)