Those are not several things but 6.
R1 was not released as the surveyed bulk buyers and other 1-Series customers from 2017-2019 prefer SLRs.
That may have changed within the last 52 weeks but the question I'd pose is is Canon willing to take the financial lose of
Osborning the 1D X Mark III and Series III EF 600/4 & EF 400/2.8?
Now, if Canon released a RF 600/4 & RF 400/2.8 in 2018 instead and R1 in 2020 instead then that would have been better.
I have no doubt that the MILC tech for the R1 has been there for more than 2 years already but what is needed to support a 1-Series body is the appropriate lens and accessories for it. Thus far only the three L f/2.8 zooms are there. No white long fast primes.
Nikon themselves admitted that their transition to MILC was slow. By my estimate by 2 years. Canon was late by 1.
Sony timed it perfectly. Their FE 400/2.8 came out in 2018, FE 600/4 and a9 II came out in 2019.