I think it is somewhat of a myth, or more to the point a hyperbole. Porting is relatively inexpensive as compared to developing a new game. That however does not mean there are not serious costs. Unless your building off a dedicated cross platform engine. Either built internally, or licensed from a third party. You will still have to fund a team for months. That means additional employees or longer periods during releases. Either way serious cash is sacrificed to port a title. Were that not the case almost every single game ever created would be ported to all possible platforms. Since that does not happen we must assume that a certain sales threshold must be reached to offset lost productivity. Such as your next game coming to market a few months later.
To be frank I think Microsoft has already passed this particular threshold. Not based upon sales margin, attach rate, or a market dominance. Their console enjoys common architecture with the PC market, and thus more developers are already considering console ports of their titles from the offset. The 360 already enjoys more exclusives then the PS3 due to this virtue. The more consoles Microsoft sells the more attractive their platform will be to what were once dedicated PC developers.
I think the 360 is already viable as an exclusive format. Regardless of sales margins due to its attach rate alone. Developers have to be looking at their time tables, and realize that the stretching due to the PS3 has probably become counterproductive. The delays only ensure fewer releases, and with the attach rate on the 360. More releases on the 360 means more money then can be generated by porting. This would be different if the PS3 had a higher attach rate, or a higher install base, but that is not the case.
The margin could only help the PS3, but it does not affect the 360. Be it eight million or twenty million. I want to be even handed, but I cannot rationally see how porting at the loss of volume plays to the favor of developers especially smaller developers. Big developers with established franchises can do it easily. They already push their volume regardless, and the name recognition ensures more then enough sales to cover costs. However for smaller developers it just isn't the case.
I don't expect to see major defections, but then again Microsoft also covets the other end of the spectrum. They will drop the coin for an established franchise being exclusive. That is where the sales margin really shines. With enough difference, and with a contract out on the table. Microsoft could secure the highly sought after exclusives. That will not happen if Sony can maintain its attach rate, and keep the margin under twelve million. Past those and it will be open hunting for Microsoft.







