Hi David,
Canon is of course not going to throw away EOS, but I believe we have a clear sign that it isn’t their top priority any longer.
Until this release my view is that it would have been just unthinkable for them to release such a landmark lens (my bet many see it as one of the best Canon lenses) without it leapfrogging the equivalent Nikon. And a large majority of Canon hardcore followers have been telling us “Canon makes better lenses”. Only admitting a possible Nikon superiority on a given lens as a temporary thing “that’s because the Nikon is newer, Canon is going to better them at the next iteration”.
“Well, Canon is now focusing on their mirrorless line up” is IMHO the obvious message here for an objective observer. And, again, this is probably the right decision for them.
Nikon released the best film camera ever, the F6, years after Canon stopped investing in film. It shouldn’t come as a major surprise that they continue to invest in DSLR lenses after Canon diverted their efforts towards mirrorless. Canon is probably right and Nikon probably wrong.
One doubt this introduces though is whether Canon can catch up or not. The Nikon version of the 70-200 is the best zoom lens ever released, getting incredibly close to the Otus at f2.8 on the D850, meaning that it is a 100mp ready design. My belief is that Canon could do better still, but by deciding not to, they are putting themselves in a slightly uncomfortable position.
Now they have been serving their customers with second tier sensors for years, it seems that they may consider them as being unable to tell apart very good from great and/or that their long term profitability is more important than making sure their users get the best lens money can buy in front of the best sensor driven by the best AF.
Future will tell but I am 99% sure to be right on this one.

Cheers,
Bernard