For the record, I'm only referring to sales. Last generation, nothing was even remotely close to the PS2.
In terms of what the PlayStation 3 platform offers, I firmly believe it's on top. Between the free Network, Blu-Ray, solid reliability, a controller I prefer, and an unassailable list of software, the PS3 remains my system of choice. I imagine many PS3 owners feel the same way; just want to clarify that in regards to quality and consumer appeal, nothing tops PlayStation right now.
The question in the headline only asks if Sony can ever reclaim the top worldwide sales spot. We may never see another PS2; in fact, I don't think any manufacturer will dominate like that ever again. But can the PS3 eventually top the Xbox 360 in the total sales count? Sony has definitely narrowed the gap over the years, especially in regards to most every region on earth outside of the US. Or will we have to wait until the PS4? And when that arrives, will it top Microsoft's next effort? And the Wii U or whatever Nintendo happens to have at the time?
If Sony launches after everyone else again, it seems unlikely. Some believe Microsoft wouldn't have the lead it has if it hadn't released a year ahead of the PS3. And what about the PlayStation Vita? Will that help put the PlayStation brand at the top of the sales charts, or will it be all DS all the time? I don't have answers to these questions; I'm merely asking them. 😉