Yes, I do not understand why the R3 has two different cards. For professionals it is quite annoying to have two different cards for redundancy and if one of them is slower, redundant writing to both cards can only go as fast as the slower card can handle it. Imagine you really want to write 30 images per second in RAW+JPEG to both cards. Can the SD card in the R3 do it? Of course it could also write on the faster card first and then copy it to the slower card directly after the shutter is released. But that would be risky if the faster card is already faulty.I am 100% sure R1 will be a sports-oriented camera unless there is a separate R1X.
If R3 was a 1DX replacement then it would have 2 CF Express slots.
Maybe we will even see an R2 released together with the R1 like the R6 that was released with the R5.