The section on deprecation appears to say that the service may be deprecated without a deprecation period "providing the Deprecated Version of the Service could create a substantial economic burden as determined by Google in its reasonable good faith judgment". This is the explanation they used for deprecating the translate API, "substantial economic burden". Nobody is going to be able to argue against Google's "good faith judgement" on this point, so it sounds to me like this service could effectively be deprecated at any time.
In an act of self-fulfilling prophecy, I'm sure this will be shut down for "lack of use" (since Google APIs are now all radioactive)
Is it just me, or are Google's APIs becoming more farcical with every revision? I see these words before "API" that you just wouldn't think belong in that context. Now "Prediction API". It makes me really excited for the next batch.