You're right - this is very reminiscent of the Microsoft Antitrust suit of 1998. Technically, per that ruling, Google could be subject to an AT&T style breakup. However, it's pertinent to note that on appeal, the Justice Department chose to settle with Microsoft on the issue of splitting the company rather than go back to trial.

Clearly, in the real world, the ruling didn't stick, as today Microsoft, Apple, and Google all package their browsers on their operating systems. As such, I don't think it likely that enforcing an API standard would exceed the current antitrust abuses that we've come to accept as a fact of daily life, and highly unlikely to attract a serious case from the Justice Department.

That being said, I fully support your effort - we've needed stronger antitrust enforcement for a long time, and AT&T shouldn't have been the high watermark of the Justice Department's efforts in this arena.