One of the
reasons of namecoin failed was that most people don't care on whether the domain they visit is centralized or not. Having a working solution is not enough to convince people to use it.
Also, I'm not sure is it really worth it. Not everything what is on blockchain is safe or having enhanced level of security and privacy. But in fact it would have almost the same cons as centralized domains do and authorities would now allow it to work out of their control.