Unfortunately I am having the same problem...i got so excited when i saw the press release saying it was available "now" -- unfortunately it is not.
I Haven't been able to confirm this but it looks like it's true -- they are doing a staggered roll out for NBC Sports, a few people at a time...I'm not sure why.
i Don't believe that it "crashed" -- live Extra has been available for iPhone and iPad for a long time now and so has their web service -- they all use the same back end...I can't believe that a few Apple TV users who actually clicked the app icon when it launched earlier this week crashed it compared to more than likely hundreds of thousands of web / ios users That have been using this app since it came out (months now), which continues to work just fine.
I Never had any issues with the HBO now app going away...it's always worked for me since launch.
OH well...guess it's AirPlay again for the Rangers game tonight. The crappy thing about using AirPlay is that while I'm airplaying it from my iPhone to my Atv I can't use the iPhone at the same time: I can't even put it in sleep mode Since the NBC Sports app stops playing video unless it's the only app open and in the foreground. Putting the app on the ATV seems like the perfect solution...guess I'll just have to wait 😟 /me pouts