What is an open question is whether 4e's life-cycle was short because it was different or simply because ten year editions are no longer financially viable. Time, and 5e, will tell...
I'll take option C: both. I think 4e ended up having narrower appeal than expected/hoped for, and certainly narrower than 3.x. But I also don't think we'll ever see a 12 or 11 year cycle again like we did with 1e and 2e.
That said, the cycle might be less important as how compatible editions are with each other. 1e material was still quite usable with 2e, and the same, of course, is true with 3e, 3.5, and Pathfinder. I would expect that WotC's goal isn't as much, or only, to make an edition last much longer than 4e, but for whatever comes
next (6e) to be resonant with 5e. This is one of the reasons I think they've been trying to create a simple core for 5e.
If I had to guess I think we'll see a "5e revised" sub-edition in a few years, depending upon how much errata and broken areas there are in 5e. If they call it "revised" it might be less controversial than "5.5" which brings back back memories for many. "Revised"
can be interpreted to mean, "We just want to make it better for you."