Well, the day is finally here. In an interview with the Japanese press (https://www.yomiuri.co.jp/economy/20211228-OYT1T50000/), CEO Fujio Mitarai says the 1D X Mark III will be the final Canon DSLR in production, and when it ceases production that’ll be it. There will be no future 5D after the current Mark IV and no new 7D.
This is not surprising really. Mirrorless cameras have increased in popularity while the mechanical/optical cameras have been losing out. In fact, overall sales of professional and prosumer cameras has been in decline for quite a while. I suspect the smartphone's increased capabilities as a viable camera platform has a big part to play in this as well.
My first toe-dip into digital was a little Hewlett Packard digital point and shoot around the year 2000 or so. Probably a 2MP camera. My main camera at that time was my venerable Nikon F2AS. I bought a Nikon D100 around 2002 and used it until it failed out of warranty. I replaced it with a D70 in 2004 and it also failed out of warranty. After that I did not bother with another DSLR for a number of years. That next camera that I use to this day was bought in 2008 and is the Canon 5D MkII.
Times change and technology rolls on. At some point the same will happen for Mirrorless cameras and cinema cameras. Something cheaper and better will be developed and the need for dedicated professional/prosumer tools will be relegated to the dustbin.