Note, this is Redbadge, I accidentally posted on my brother-in-law's account while at his house:
Now that I'm on a proper computer, let me revise my analogy.
To be clear, I don't think Magic really has annual "editions." Magic 2.0 was never announced; it would have been suicide (you think the edition wars are bad?!). Magic is just Magic, regardless of the number of "editions." However, Magic in 2014 is significantly different from Magic in 1994. The changes have just been incremental enough that few have noticed or cared (although a number of people have decrietd "the death of magic" with each major new change from the beginning).
In the same way, Dungeons and Dragons will look significantly different, if still recognizable, 20 years from now. With each year, splats, errata, and changes will be introduced, even in an evergreen scenario (assuming WotC actually intends to sell new stuff every year). Hopefully, a new set of Core Rules will have been published one or more times in the interim.
Honestly, the model is not that different from what has been tried in the past: core rulebooks, supported by splat, refreshed occasionally by rules updates and new editions and new "half editions."
However, the point I'm trying to make about Magic is that when WotC introduces a new expansion, a new core set, even a major new rules overhaul (planeswalkers, Commander, etc.), people don't argue (for the most part) about the new changes or additions. They don't say, "So are you switching to Khans of Tarkir or sticking with Theros?... Well, I've already got so much buy in on this edition and don't like the new mechanics." For the most part, they just accept that these things come every year and just pay out (lots, in the aggregate) of money so that the Magic juggernaut marches on.
My conjecture was that WotC would like to match this dynamic with D&D going forward, such that periodic "edition" changes are whole-heartedly accepted and expansion material rakes in the dough, in perpetuity.
Any points about switching costs and length of play with regards to Magic seems to mimic the direction they are trying to go in D&D with quicker, more stream-lined character creation, play, and character advancement in the newest edition, such that you've finished a campaign with your druid (about 8 months) by the time the next best thing comes out. And just like people will always play slivers at the Magic table, there will always be someone to play the basic classes no matter what the newest thing is.