Jeffrey Zeldman points to a discussion at MacCentral forum as justifying Apple’s decision to extend the life of OS 9 "a bit longer". As I read the discussion, these people have no intention of ever switching to OS X, Quark or no Quark.
Elsewhere, John Gruber wants Apple to replace the OS X finder with one that "builds on" the one in OS 9:
So imagine if the OS X Finder were redesigned to appeal to Mac OS 9 users. By simply changing nothing other than the Finder, the entire “Mac OS X” experience would instantly feel much more familiar to millions of Mac users.
Of course, it would instantly feel more foreign to switchers like me who’ve never used the “classic” OS. It’s becoming apparent that many Mac lovers will never willingly switch to OS X. They don’t like the Finder, the dock, the icons or the muli-user underpining. I suppose Apple can continue shipping OS 9.2 for years but I think pressure for revisions to the old system would begin to build. Even Microsoft couldn’t justify development on two separate operating systems forever; Apple can’t afford it at all.