We've known about this for a while and I'm not sure what Deadline was talking about regarding Young Justice S3 going to Netflix, AFAIK it was brought back specifically to 'anchor' this new service, which has been planned for a while.
The only surprise is The Teen Titans show appearing on it. I'd been hearing for ages that WB were actively developing a Teen Titans (called just 'The Titans' apparently) film for a while and were chasing a big name director to helm it. Now, there could be a couple of possibilities.
A) This was before Nightwing was announced so it's possible that everyone got their 'wires crossed' and this is what the rumours of a Titans film were.
B) WB are no longer planning a Titans film at this time as they are moving some parts of the DCU around (hence the Black Adam announcement) and everything is in flux.
C) They are still developing a Titans film and, just as they are with The Flash, they intend to run the pair beside each other reinforcing the 'multiverse', splintered brand, idea.
But in saying that if Warners really want to make a go of this they really need to push the boat out for this Titans show and by that I mean production values close to what we see on big 'AAA' shows on pay cable and Netflix etc.
If WB/DC are jut going to slap a Titans series with CW level production values they might as well quit now. This needs to be their signature series and make a big noise right out of the gate a bit like CBS are intending to do with that new Star Trek show.
Guys. It's a DC digital TV service. For DC content. Just DC content.
For what it's worth when the rumours of this first started it was described as a "DC platform" which many assumed to mean all of the previous animated and live action DC film & TV shows (within reason when it comes to CW licensing etc) complete with access to DC comics using a Netflix style model and some other content.
With everything they've done (previous cartoons, films and even obscure stuff) there is more than enough DC related content over the years to fill out a subscription service.
But..., things change and it could now be something else but at the time no one was describing it as "DC Netflix". Rather it was Comixology with scripted/TV content.
We'll see.