Coming to this thread late, so just a few thoughts/comments about things that have been discussed:
1. I saw the Hollywood Bowl production, and Ana Gasteyer (an actor from SNL) was freaking phenomenal in that role. Best Hannigan I've seen, personally (the original was before my time). That isn't to say that she'd be my first choice for the broadcast - I'd rather they get someone who hasn't played the role. But I just wanted to chime in and vehemently disagree with any speculation that she might not have been up to the task.
2. Love the idea of racially diverse casting, but I'm not a big fan of an David Alan Grier in general, and I thought his Warbucks was just ok.
3. Annie is more than 2 hours long, but certainly never hits the 3 hour mark, or even gets close to it IIRC. It probably sits comfortably around 2h30m. For my money, I think the trimmed 90 minute book works somewhat better than the full version, though I think there are some nice moments lost.
4. Annie is a bit of a guilty pleasure for me, so I'm sure I'll end up watching this (and probably loving it) despite the fact that I generally don't enjoy these TV adaptations.