You've really got to wonder if this defeat, and the one-sided nature of it, will effect how much longer decides to stay around in the game. Had it been close, you could've say that maybe the next time Agassi runs into Federer in a slam he may finally pull ot the win.
But when you take note of the fact that a) Agassi, as he himself put it, did not make a 'dent' in the Federer game b) It was on Agassi's best surface and c) Agassi has now lost his last 5 meetings with the Swiss man, you reach the conclusion that Agassi will never beat Federer ever again, even if Andre plays his best (he was near or at his best in yesterday's match) and Roger is below par. The problem is that Agassi is excellent in most areas of the game, but Federer is EXCELLENT IN ALL ASPECTS.
The fact that it is impossible for Agassi to beat Federer is a great problem for Andre's 9th grand slam hope because, at the moment, you have to beat Federer in order to win a slam. The player who does eventually beat Federer in a slam is going to get MAJOR CREDIT.
And even if Federer's level of play does drop off or he becomes injured and Agassi finds himself in the position of having a shot at a slam title without any prospect of playing Federer, it's still stretching it to say that he would win it because there would still be an extremely strong field left (Safin, Hewitt, Nalbandian , Roddick, Nadal etc.)
Agassi will, of course, maximize his chances of another slam through superb fitness and excellent scheduling decisions, but the chances of him actually pulling it off are, sadly, less likely than ever in the last seven years. I'm not saying it is not possible, just that it would require A LOT of factors to go in his favour in order for it to happen eg. short matches up until the quarters at the earliest, a draw that avoids hard players until very late on, etc.
Maybe yesteday's defeat may make Agassi think that it is not worth playing on till next year, but even if there is only a 5% chance of him winning another slam I think he should - retirement should only come when he is 100% certain there is no chance.
But if he does fail in his quest, there's no shame in it, Agassi's place in history has long been asssured.