Just playing Devil's Advocate here, and I have NO info to back up my prediction, but I wouldn't be surprised if Disney/ABC had some kind of special planned, but a decision was made to delay it until a sweeps period. Yes, it would make sense to have a special air the exact anniversary day of Disneyland's opening. At the very least, you'd think they'd air some kind of thinly-veiled infomercial in prime time. But that's not the case.
Unfortunately, Disneyland, while being the first, does not have the cache, the appeal, for many people that WDW has. Therefore, just like all the other Disney parks are celebrating the 50th. anniversary, I would expect a big special that would spend just as much time in Orlando, Paris & Hong Kong as they do in Anaheim. And to shell out the kind of sheckles it'd take to produce something that big, only to "bury" it in the traditionally dead summer months would be anathema to show biz. Hell, I would've assumed they would've done something this past May in anticipation of the 50th (maybe they did, but I don't remember seeing something on it, and I'm the sort of Disney nut where, if a special was on, and I didn't know about it, anyone I know would tell me). But I wouldn't be surprised to see something for November sweeps.