And how is APS-H any better? I always felt like it was the worst choice for wide-normal FLs (the ones you would normally use on a mirrorless camera). There is no decent non-L fast-50 Canon equivalent for APS-H (IMHO 35/2 is pretty bad). I guess that 28/1.8USM is a decent 35 on 1.3 crop, but that's all... It may be acceptable if they produce some nice APS-H format primes (like 12mm, 28mm, 40mm, 75mm), but then again it would fail at adapting EF/EF-S lenses (in term of vignetting, black edges and awkward FLs) and that's a deal-breaker for someone like me.
I shoot FF most of the time but I still enjoy shooting with my 1DM4 which is, of course, APS-H. In a mirrorless body I'll take the largest sensor Canon is willing to put into it and, yes, I do shoot with L glass most of the time. I'd be quite happy with a 1.3x sensor mirrorless body to use with the 14/2.8L, 24/1.4L, 35/1.4L, 50/1.2L... you get the idea. Don't get me wrong, I'll take a mirrorless that is FF but I don't think Canon will produce one. I don't really think they'll use APS-H either, so it will end up being something that I may buy as a backup for traveling light but not as my primary camera...