We have been told that Canon has “accelerated” development of the “pro” level EOS R camera, and we're not talking about the high-resolution model that we expect to see in late 2019 or early 2020.
This new camera will be along the lines of a mirrorless version of the Canon EOS-1D X Mark II (or III).
The source also mentioned that it is possible this camera could be announced alongside the EOS-1D X Mark III in the first or second quarter of 2020. Though the date of the announcement is a long way from being decided.
Announcing these two cameras together would be a unique move for Canon, and while I think it's possible, I suspect we'll see a development announcement for the EOS-1R X (as I feel like calling it) well before the actual camera ships.
An EOS R professional body with some new RF super-telephoto lenses at the 2020 Tokyo Summer Olympics next July could be a great time for the launch of pro-level EOS R and RF mount gear.
The R-equivalent could be very interesting - particularly how they get it to mimic the qualities of the existing 1DX line.
We'll absolutely get an EOS-1D X Mark III. Professionals that live by the EOS-1D series of cameras will be the last to move to mirrorless in my opinion.
Or maybe Canon has a plan to release 1-2 L more telephoto lenses?
We probably will have 24-70 and 15-35 f2.8L so I don't see huge problems there.
(Not that I’ll ever, ever, in a millions years, be able to afford it)
Not really. Most professionals will be using this alongside their DSLRs. The adapters work fine and unless and until you are ready to dump all DSLRs (which is a long ways away for most pros) it's likely that R lens sales will be limited to a few key lenses.
A 1-DX equivalent mirrorless will not underperform in either autofocus speed or accuracy. If DPAF data is the issue, then Canon will either 1) have innovated beyond DPAF, circumventing the problem or 2) will have increased processor throughput to handle the data.
The holy trinity lenses will be there in time for this body. You'll also have an 85 and 50 1.2 and a 35 1.8, all RF mount. Short of supertelephotos/teleconverters that covers every major category of lens reasonably well from 15 - 200mm and wide/medium/short tele fixed, though a 24 1.4 (or perhaps 1.2?) is a bit of a gap for some people.
RF mount needs L telephoto lenses (1 or 2) before EOS RX (or what ever it'll be called).