Then of course there's the third theory... they might not know what's going on either, and are unable to comment because they don't have any information.Disney may just not be commenting to the public, it may even be a standard policy not to. It doesn't mean they are avoiding it. I'm sure something will be said sooner rather than later.
Now, I have a feeling that Steve couldn't have been fired, nor would they replace anyone with sound-a-likes. Why? Because Eric, Bill, Dave, and other Henson employees are still there, and they've been performing the characters at D23 last week. Now, if Disney were to have problems with Steve, wouldn't it just make sense for the other performers who have worked for them so far to get angry enough to quit or "strike" out of solidarity? And if they were indeed replacing them with sound-a-likes, why would they keep said performers around? Somehow that just doesn't add up.
So far, we've basically seen 2 performances without Steve... and frankly, 2 live performances within a week of each other, while unnerving, doesn't really say much about if Disney's replacing Steve or not. Maybe he's busy with something else, maybe he has a personal matter (which, at the risk of sounding mean, isn't any of our business).
And again... hypothetically speaking, if Steve decided to move on and he gave his blessing for someone else to play the frog, wouldn't we support that? Sure, I like Frank Oz as a muppeteer and all, but I respect his choice to have a film career (yes... even that Stepford Wives movie), So, if somehow Steve made a choice to leave by his own will (hypothetically, since we know nothing yet), shouldn't we support that as well?