I wasn't aware older editions had died.
The Internet certainly bears out that older editions are alive and well. I think WotC needs to realize that they need only flip the switch (reverse their older edition PDF policy) to become a player again in those markets. I doubt it would take much to get dtrpg/rpgnow to plug them back into the system. I'm sure the coding is all still in place but simply not accessible from the outside. Anyone who purchased even a single older edition product through those storefronts knows that at least the record of those purchases are still in their system.
It's odd to me that they don't simply do so rather than make cryptic tweets like, "We are looking at ways to keep ALL editions of #dnd alive." The editions are alive, WotC just isn't a participant in those lives. I suspect they are looking at ways of boosting DDI membership by incorporating older edition materials through that medium and perhaps considering some limited new release support also, and exclusively, through that medium. Why else be so coy? A possible DDI connection would make more sense for the manner in which they are approaching the subject. While I think this approach is less of a draw for most who are currently the ones keeping older editions alive, I also don't think anyone championing such a move could garner an in-house concensus at WotC unless it includes a DDI component.
Additionally, I doubt we would see anything along the lines of licensing akin to the d20 STL or OGL for people who produce 3rd party products for retro-systems (official older editions or not). By the same token, I doubt anyone would take them up on a licensing deal unless the licensing was completely free of strings and irrevocable. WotC's venture with the GSL seems to indicate that it is unlikely they would do licensing any other way. Regardless, I doubt that a revocable licensing scenario would garner much support, given the risk versus reward. Very few 3rd party players, if any, could hope to see an increase in sales of any real significance under any sort of licensing scenario and the risk of having it pulled out from under you down the line is something no one would be blind to recognizing no matter what Pied Pipers or evangelists emerge to wave the banners.
It may be this is all about mending some fences and that some limited older edition releases (and/or re-releases) through DDI are all we'll really see. I'm not sure how much would be gained but it would at least be an olive branch that might get them more feedback from older edition players as they move forward with their marketing and fine tuning of 5E, street cred they seem to desire as they have been testing the waters with their recent marketing forays. They've gutted their institutional memory from the staff so if they wish to market 5E to older edition players they will need to have some basis for saying they understand what those players want.