I'm just not convinced that it is out of the realm of possibility (note I am not saying "likelihood"!). The best PR firms have brilliant campaign creators that can sell ice to the eskimos. Evidence ~ look at the junk they sell the public on a daily basis! These people are wizards in their ability to convince the public to buy "New Tide" for the umpteenth time.
And as you said, Apple pulled off their resurrection with the "Think Different" media blitz 20 years ago.
But admittedly it would be a longshot, and would not be cheap. They'd need to employ new & very hip spokespeople; new & very eyecatching interface; the kind of media commercials that people tell their friends about; designer Yahoo t-shirts, bookbags, ballcaps; joining with other cutting-cut partners for a full & unrelenting assault on the status quo (read: Google); daily stories in the press playing up the rivalry.
They have to make it a WAR and fight it on all fronts. They may in fact fail, but they'd go out with a bang, not a whimper ~ a more noble end for a one-time contender.