why do people think 360 will come in third?

[shams]

As its been stated, its sort of a question of definition.

I think the 360 will come 3rd, purely because MS is likely to launch the successor to the 360 before Sony will launch the successor to the PS3.

The 360 may still be ahead in WW sales at that point - but sales will (may?) drop off quickly after that, where a PS3  sales will continue to build as the price continues to drop. 

If Sony surge ahead of the 360, MS is likely to introduce the next console sooner. But as long as the 360 is solidly winning in at least one market (US) MS won't be as stressed to do this.

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If the PS3 continues to underperform, Sony will have to do something drastic - I'm not sure what. The PS3 is more than powerful enough for a console, so apart from reducing costs (which they are doing now!) there isn't much else they can do.

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The other issue for the 360, is that the PS3 has already won Japan - and looks like winning Europe. I still believe MS did a great job of squandering their 1 year lead - and the RRoD issues haven't helped either.

MS are relying on the US market for the bulk of their sales at the moment. If this ever starts to change - the 360 will be in trouble, and its days numbered.

But for now - the challenge is in Sony's hands - not MS's. Even with the new models, drastic price cuts (slashed 1/3rd of the price, in less than 1 year on the market!) the 360 is maintaining a comfortable lead over the PS3 - and has a significant (and growing) software advantage as well.