Shams, great breakdown. I have also been wondering about why major franchises have been declining in past years. I think it's mainly due to PS2 dominance waning but there is probably more to it than that.
God forbid, it might be the maturation of the gaming public. Really, the only widely received sequel this year has been Halo 3, and for good reason. It compounded on previous elements and then offered a load more for gamers to enjoy. Most of the previously huge franchises have been from the Japanese, a gaming culture that largely seems unwilling to change. I think we'll only see western games get bigger from here on out, just as we've seen for the past decade.
Overall, I hope this trend continues. We need less FFXXXX and more BioShocks, Mass Effects, Uncharteds, and other new IP. This industry is poised for some real change in IP, gameplay, and environment. The DS has provided the environments, the Wii has provided the gameplay, now we just need some killer IP (and not just the fresh-but-cool "same ol' same ol') to flesh it all out and grow gaming as a whole.
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