If Sony wants to be on top again, they've got a lot of work to do. Believe what you will about comparing PS3 sales to PS2 sales, etc., but Sony REALLY screwed up the release of the PS3 by 1.) not making enough units to even approach demand, 2.) making the price way too expensive, and 3.) not having enough good titles lined up (which holds true even today, almost a year after release). In addition, any exclusive titles that Sony could've used to its advantage have jumped ship to the Xbox 360 to increase sales (except for Ratchet & Clank and Metal Gear Solid 4--and MGS4 has expressed interest in making the game for the 360 as well).
Now, you are correct in saying the PS3 has a lot of potential and that it's yet to be unlocked, but that holds true for the 360 as well--game developers are still "recovering", so to speak, from learning to create games for previous-gen consoles. In any case, it's not looking too good for Sony, and I don't think they'll be the leaders in the console market anymore--but 5 years is a long way off, so who knows? Like I said, they've got a lot of work to do, but it's looking like Microsoft and Nintendo are going to be duking it out for a while first.