I've come to believe that many of us who hang out in CR forums are gearheads.

So, I have no idea how many photographers think like we do. For me, the idea of buying a new EF lens is not as attractive as it was before RF was released. For example, for lower-light events, I'd like a wide angle lens faster than my 16-35mm f/4L IS. The current options aren't all that exciting, but even if they were, I'd hold off and wait for an RF version,
even though I don't own an RF body yet. I can do fine with my 24-70mm 2.8 in most situations, and use flash pretty often when I need to go wider with the 16-35mm f/4.
I don't own an RF, but I'm going to someday, so I don't think even a great version II of the ef 50mm f/1.2L would tempt me much. But I'd plan to buy the RF version pretty quick when a 5DIV type of RF body comes out.
And so on. Any lens buying right now is complicated by what
might be available in RF soon. But I doubt many other photographers think like this. Probably more of them just get the lens they need or want when they need it.
So, if all photographers were like CR members, I'd agree with your numbers. Seeing as how CR regulars are (relatively) obsessed with tech and specs, I don't think we represent the market. Therefore, I would flip your numbers over two years, or maybe say at most 35% buying RF versus 65% still buying EF.
At some point, though, maybe three or four years from now, RF ownership and interest will hit a critical mass, and then we'll see EF fading away as the legacy technology it has become.
We don't seem too far apart here.