I don't get this argument that the early-to-mid noughties was a harder time to win slams than the present. Yes, Federer was bloody good back then, but who else was actually comparable to Djokovic, Nadal & Murray and their respective levels presently? There were a bunch of bit-part slam champions back then such as Hewitt, Roddick, Ferrero, Gaudio, Johansson and Safin. Doesn't that just illustrate that it was not too difficult to sneak a slam or two in despite Federer's dominance?
You have a point but as has been illustrated before countless times in this thread, due to the court surfaces not being homogenized yet the aforementioned players were extremely dangerous on their favourite surface (eg - Roddick at Wimbledon, Ferrero at RG, etc). You still had to play at a remarkably high level to snatch a slam, relative to the era, racquet technology and surface prowess of the top players.
As for the thread question, Murray has to win another slam and spend some time as world number one. Will he do that? I think it's a resounding yes...