Netflix serves more than their own home-grown content.
Not sure if their plan is to license other content or just rely on their own. If it's the latter I don't think it will be much of a Netflix competitor, it will be more like HBO Go. Otherwise, if I was Netflix, I'd be very worried. Disney has some deep pockets!
I think they are set to launch in 2019.
All of the Netflix original Marvel shows alone may be a reason they can "win" just by taking all their balls and going home to a streaming service they control. They've already admitted that all of their current contracts with Netflix have been set to expire in 2019 precisely for this launch (and presumably a part of why this still unnamed service has such an explicit but two year away launch date).
That's just Marvel's relationship with Netflix. Factor in all of Star Wars, the Miramax back catalog, the Buena Vista back catalog, Pixar, ABC, and of course the Disney brand itself. (…and potentially now the entire film and TV catalog of 21st Century Fox is on the table to be controlled by Disney going forward.)