My fear is that they will succeed, not fail.
For one, it's easier to pacify the populace with a bit of economic freedom and no political freedom than to acqknowledge both the former and the latter.
I think the experiment could fail due to a SARS epidemic. Freedom of speech would undoubtedly help the medical community fight an epidemic; absence of such political freedom (resulting in a propaganda cover-up) may ultimately cost thousands of Chinese lives. The lesson is about to be driven home that political freedom isn't a 'threat to political stability,' it's a vital feedback mechanism to prevent a society's government from doing something really, really stupid.
But how new is this really? What the Chinese leaders are apparently turning China into is very much like what the media generally call a "right-wing" dictatorship: some economic freedom, no political freedom, lots of bureaucracy and corruption, and brutal treatment of those viewed by the government as enemies. [Needless to say, despite the media appellation, this has nothing to do with true right-wing political thought based on principles of individual liberty.]