I bought the original R in 2018 while I also owned a 5D Mark IV and an 80D. At the time, I intended to keep the 5D and probably sell the 80D.
Six weeks later, I had not touched the 5D4 once. Re-thought my plan and decided to sell the 5D4. Glad I did at the time because I got more for my used one then they sell for new now. Sold the 80D a short time later as well.
Ended up buying a second R. Sold one last year and picked up an R5, thinking I would do an R/R5 combo. Shortly after using the R5, decided it was too much going between R and R5, sold my second R for an R6 and haven’t looked back.
I would honestly be surprised if Canon released any new DSLR’s at this point. Possible exception being the consumer “T” series crop bodies to keep market share in that category. I imagine they will continue making the current models in the upper lines (90D, 5D4, 1DX3) along with the current EF and EF-S lenses but I think they will be end of the lines models with focus shifting to R series bodies and RF lenses.