It will be hard for WotC to succeed with their "all things for all people" unifying game set. It would have been much easier to follow up 3rd with such a ruleset; the drastic changes in 4th will be tougher to fold in and maintain the goal of a non-fragmented player base. At least, if their definition of non-fragmented player base is lots of people playing essentially the same game, as opposed to lots of people playing a game with D&D on the cover. But if they get back the majority of Pathfinder's market, and only a handful of the old-school market, I am sure it will be considered a resounding success anyway.
As much as I hate to say it, given my love for 1E, if I was a Hasbro executive I would make the original Moldavy/Cook B/X set the evergreen Wal-Mart game that is truly within the grasp of 10-12 year olds to run and create for, 3E the "advanced" game, and keep the guts of 4E as the spiritual heir to Battlesystem - something you pull out when the campaign takes a turn from dungeon combat to battlefield combat. I wouldn't spend a lot of money on making up new editions. Support the IP you've already paid for. The OSR has proven that if WotC would put out good material for B/X, anyone playing a pre-3E game could spend their money on it and use it essentially as-is. Viola, revenue from all sources.
If Wizards could ever crack the VTT combination, that gives a DM a BTB-starting point easily modified for house rules, seamlessly running the preferred edition, I think they could have a gold mine. I would bet that many gaming groups that have been out of the hobby for 20 years are still connected due to the wonders of facebook. Something like that could get people interested in getting the old gang together again online in a way that even Google+ doesn't currently do; and the number of lapsed gamers probably exceeds the market of current gamers by a factor of 20. There's your gold mine.
But me? I've got what I want: Matt Finch; the collective authors of the Advanced Adventures line at Expeditious Retreat Press; PatW of ASE fame; and others are making what I want. I'm not going to accept less so that I can be supporting WotC. They have to earn money that is already considered well-spent.