Adobe should have done this a long time ago. It would have been much better for them to have just gone "Actually, you're right... Flash is kind of crappy. Let's embrace HTML5". They just chose the hard way. They've ended up going down the HTML5 road anyway.
Looks like they did exactly that. From looking at this, Adobe must have made that decision in (maybe) late 2009 Do you think they wrote this in a week? Software like this required many thousands of man hours to write.
If they do drop Flash it will only be after their replacement is very mature.