We have some long-term plans to improve YouTube support (not sure when I'll finally get to it, so much to do!), but something entirely commercial like Netflix is very hard. They have rather strict DRM requirements, which makes them extremely wary of PC-based solutions entirely, requiring modern hardware DRM support for their highest quality in browsers, which for us would mean that even if we could somehow cooperate with them, we would ultimately be building an entirely new Netflix client inside MC, and it would still be rather "external" and not feel like MC itself.
Considering that 2019/2020 are the years where Netflix really has to fight for its space more then ever now with other big streaming services starting up and pulling their content out of Netflix (eg. Disney+), it seems unlikely they would want to risk such a thing.
Unfortunately this really applies to all commercial video streaming. They would all be happier if they didn't have to deal with the PC at all, and could all run on closed-down set-top-boxes.