Actually, Apple has a decent chunk in the desktop video market cornered -- but it's not the defacto standard, yet (regardless of whatever magazine is claiming). While this market crosses over into the high-end market, television and production companies use Media100 and Avid products (not to mention others) as well.
And as great as DVD Studio Pro is -- the majority of all DVDs that are produced are done on PCs -- hence the massive amounts of DVDs that come with special DVD-ROM features that work only on the PC.
I would dare say that After Effects and Photoshop will never leave the Mac -- they have carved a niche for themselves that offer a certain level of usability that no one else can offer*. Apple is going to have a hard time convincing people to move to Shake especially when companies like Pinnacle Systems, Adobe, Discreet, et al offer quality packages like Commotion, Combustion, After Effects, and many more.
That being said... most companies don't limit their tools to just one product. Quite the contrary. They tend to use at least two (or more) of each type of product, because more often that not, each package has a specialty/nuance where the other stumbles.
I had the opportunity to check out a local production house in Ottawa called TV Factory who rarely use Final Cut (if at all... since the last time I was there) for their work, but use Media100 and AfterEffects almost exclusively.
Some of the appeal of Final Cut Pro, in part, is the ability to use in on a G4 laptop while traveling... slightly harder to with products come with hardware components.
* Part of the reason why people love Adobe products is their GUI and Workflow -- many have tried to duplicate their workspace and have failed (or were sued for infringing on their patented properties; ie:Macromedia's "Tabbed" palettes).