Honestly with owning a R5, I realize the only thing I really need in a camera is an RF mount version of my 1dx2 so that I can go fully RF mount.
It honestly makes sense to view this as an upgrade for people still using the 1dx, 1dx2, and 1dx3 but wanting to move to RF mount.
With that in mind, you're nearly doubling the 16 FPS of the 1dx2 with the R3, on top of the durability of limitless electronic shutter, RF mount lenses, new huge and super fast EVF, built-in wi-fi, the TouchPad AF on button, a 4 mp increase, tracking focus, flip screen, the list truly goes on.
All that put together, it's honestly a compelling upgrade for 1dx/1dx2/1dx3 users. I'm sure at 24 megapixels this is going to be a blistering fast and responsive camera that gives you the same responsiveness as a DSLR, and possibly a similar sort of battery life too.
I don't honestly need anything more out of my 1dx2, but it will be an incredibly worthwhile upgrade for me to get a similar camera to the 1dx2 but with an EVF and RF mount.
If Canon didn't make a camera that was a direct update along the lines of the current 1-series, what would those users feel comfortable upgrading to? A lot of that market isn't looking to deal with 50 mp files at 30 fps.
Now that they have the R3 though, I think it frees Canon to do whatever they want with the 1-series and not have to strictly worry about that market.