In answer to the thread question:
Signs are that the 2008 Realms will change significantly in feel and design sensibility. Given this,
If Rich Baker, Bruce Cordell, Rob Heinsoo and the rest of the in-house team can, in a couple of years, create and describe a setting that is anything like as rich as Ed Greenwood had by 1987, after twenty years of organic development through short stories and campaigns, I would be surprised.
I like Ed's world very much, and the work of those who've added to it sympathetically and creatively, from Jeff Grubb to George Krashos; more than the work I've seen of the authors of the 2008 book. So chances are I won't like the 2008 setting as much, myself, even if it's very good in its own right.
I emotionally disengaged from the current timeline over several years, so the events at the back of the Grand History of the Realms aren't as much a shock to me as to some. Some of those events I'm indifferent to. Others -- the destruction of the Weave, a powerful metaphor for the bonds of lore and love in the Realms, and not just the structure of magic but part of the metaphysical fabric of Toril itself -- I don't think much of at all.
If Wizards cease to publish the 14th-century Realms -- leaving the bulk of Ed's huge Realmslore backlog untouched, and many characters (Mirt, Sharanralee . . .) likely dead before their stories were ever told -- I'll be sad, though it will have had a wonderful run, despite my many misgivings with its treatment under Wizards and TSR. While Wizards has the legal right to do this, artistically and morally is another matter.
I will probably buy the 4E setting, and try to read it open-mindedly.
Commercially, given how often this kind of drastic shake-up has failed and how rarely it works -- never, that I recall, in D&D worlds -- it's certainly a big risk. I suspect there may be no short-term way, save an unpredictable sales surge, for Wizards to publish setting sourcebooks that make Hasbro-level profits.