I think Hussar's claim is not true some of the time, and not not true some of the time.
Well, the point is that an absence of evidence is neither evidence pro or con. Really, we can say nothing about how many people play Holmes Basic, AD&D 1e, etc., now, and the WotC "lapsed player" data is of no help in this regard.
I can speculate that there is life on a planet circling a distant star, but without any evidence upon which to base that opinion, the most we can be about it (rationally) is agnostic. We simply do not know.
Any argument that comes from a position that assumes knowledge, such as "C'mon, life must exist on planet X, therefore extraterrestrial life exists" is a non-starter. Extraterrestrial life may exist, but the argument itself has no evidenciary value.
So I think the real question would be: Would the original red box effectively generate interest in WoTC's current market?
I don't have any studies saying yes or no, but I presume WoTC has done their homework on who their target audience is, and what they want.
I would hope that WotC did their research, and the trade dress of their product, as well as the ad (if it is a WotC ad), would seem to indicate that WotC does believe that the earlier D&D would generate interest, even if it is not what they want to sell, or if they believe that it will not sustain interest.
Moreover, even if WotC now thinks that the initial 4e release was a mistake, it is fairly obvious (to me at least) that pulling back now would be an even bigger mistake.
The 4e roll-out sucked. The recent damage control has been excellent. IMHO, anyway. Essentials comes across as very reasonably priced. Again, IMHO.
WotC should stay the course with 4e/Essentials for the next few years at least, and then produce a 5e that has greater backwards compatability. IOW, someone's vision of what is best from all previous editions (OD&D, 1e, 2e, 3e, and 4e). Again, IMHO.
What they should do immediately, if not sooner, is dump the delve format for adventures. They could do so without seeming to be back-treading, and it would make it easier to create adventures with more reuse potential. Again, IMHO. YMMV.
RC