Dense housing won't necessarily fix this problem. At Beijing-levels of density, we still have lots of problems with cars and plenty of people who bike and walk (including those damn electric bikes).

It works well in the Netherlands because the density is high but "not that high," and bikes are given good infrastructure. Even then, self-driving cars will be a big win for those times when you really do need to drive somewhere (e.g. to go shopping, fill in gaps of good transit, and so on).