For historical context, according to the Canon Camera Museum (https://global.canon/en/c-museum/), the EOS/EF system was introduced in 1987. The last FD lens to be released (New FD 200mm f/1.8L) was released in 1989, and the last FD body (T60) was released in 1990.
So there was some overlap. In the FD-EOS case, it was only about three years, but one could argue that going from MF to AF offered much more of an immediately tangible benefit for lots of people than going from DSLR to ML. As others have pointed out in this thread, Canon just refreshed a couple of its most popular EF L lenses (70-200 f/2.8L and f/4L), whereas, prior to the EOS introduction, the last new FD lens Canon introduced was the New FD 35-105 f/3.5-4.5 in 1985.
I don't know how much inference can be made from this history, but there it is. All of this took place 30 years ago, and our perceptions of technology and electronic products and "new" versus "old" have changed dramatically (thanks in no small part to savvy consumer electronics marketing). The EF lens mount has had a good run for more than 30 years, whereas the FD mount was only used for 20 (although that may not be a fair comparison, since the FD mount was compatible with older FL lenses, which had been sold for 7-8 years before that).
Canon also likes to boast of the 100+ million EF lenses sold since 1987, and that's a lot of potentially pi**ed off customers they need to consider.
About the only take-away from all of this to me is that Canon is not likely to kill of the EF mount completely within the next year or so, but beyond that is anybody's guess (although I'm sure the product planners within Canon have a strategy). I imagine that a lot will depend on how the market receives the EOS R. How quickly they follow up with higher-end bodies to appeal to pros and lower-end bodies for consumers, and fill out the RF lens line, will give some indications of their future direction.