A closer look into the Unix history has shown, that the Unix wars are not over but many incompatible kernels and Unix distributions are available. A measurement to determine the quality of a software project is to count the amount of commits. The Linux kernel is leading the statistics because it has over 200 daily commits.
In contrast, the BSD projects can't compete in terms of manpower. The amount of active developer is lower. The chance is high that on the long term projects like netbsd won't survive.