The Gunsmoke trend will continue as long as customers keep changing their minds about what the heck they think is important, or because the software needs more power to satisfy how the users actually work with it.

That certainly drove the early releases of MS Word, Quicken, Photoshop and others. Eventually, there's "enough" to work with (feature wise) and the milking really begins because the need to upgrade is more perceived than really needed...The last few releases of Word and Quicken certainly demonstrate this well.