I think the PS3 should overtake the X360 in 2010 with relative ease once GT5 comes out...

I voted maybe.
It will come down to the games. If Sony can market their games and advertise them properly, people will buy them and people that don't have PS3's will buy one. Really, it's going to come down to the software and their ability to deliver. If their sequels (God of War 3, killzone 3, resistance 3, infamous 2) aren't pushing the limits of the system and they don't come up with any new franchises that really blow peoples minds, than no, PS3 will NOT take over the sales position Xbox holds.

I think yes!

How can anyone predict that far ahead when there are even more wild-cards being thrown this year between Natal, Arc, price cuts and manufacturer motivations of which any number of these factors can change the result significantly?

The only thing I can predict with certainty is that there will be uncertainty. Even if Natal fails like a dead heap, Microsoft can still pull out price cuts and I doubt that Sony will be so keen to follow them down that road this quickly and wipe out yet another potential year of profit.

2011 is on the cards as a possibility, though we could just as easily be sitting in the same position on the same day in 2011 and wondering when the Xbox 360 will reach a 10M lead over the PS3.

By the time the PS3 passes 360 total number it won't matter anymore, the next gen consoles from MS/Nintendo will already be released.

It could be possible but I don't know. The gap is closing but it depends on what Microsoft does to counter it.

No the PS3 will not overtake the 360 in 2011 or ever.

I don't think we'll see any price cuts from either camp this year, instead both MS and Sony will probably focus on their new motion technologies to add "value" to their current offerings (Elite + Natal for $299, etc.).

The only opportunity MS has to change the status quo this year is Natal. If they can really push that and make people care, they can turn the tide yet again. If it doesn't take off, or if Sony's wand thingies counter any effect Natal might have, then things will remain as they are, with the ps3 topping the 360 by 40%+ a week.

Natal is their last chance to stay in second place. If it fails to gain significant traction, the ps3 should pass up the 360 by mid-2011. Of course, a price cut in 2011 could see MS wipe away any lead Sony might've have taken. Though I expect the ps3 will also have a price cut by the end of 2011, so it could all even out.

The PS3 will no doubt pass the 360 at some point in time. I think it's possible for it to happen before 2011 if things continue to go decently for Sony.

That article is dated July 2009, a bit old don't you think?

And on topic, I think it is too early to tell when and if the ps3 will overtake the 360 in sales, it could happen later this year or it might not happen ever, it all depends what both consoles bring to the table this year and how successful they are, simples!