I really love my EF 35mm f/1.4L II. Yesterday I almost purchased a new one as backup, believing that it is inherently better and more special than the new RF/VCM version.
Then I started rewatching and rereading reviews made in 2015 when the EF II came out. The new and old share equal image quality, except regarding two aspects. The reviews were done by "my" trusted reviewers from back then (Dustin Abbott, Chris Frost, Gordon Lang, photozone.de.) The biggest shared complaint was the $2000 USD price tag in 2015!
Where the new RF/VCM version falls a bit short: 1) Severe distortion, and 2) CA when wide open and near MFD. The distortion of the RF/VCM model, as we know, has digital corrections baked in, so for practical purposes, it is not as big a deal as some new reviewers rant about.
I asked myself, do I really want to layout $1600 USD (as an "insurance policy") on a lens first released in 2015? (How long will Canon service this lens? With care and luck, won't my current EF II last many more years?)
The decision isn't a complete "no-brainer" for me, as the main reason I dumped the version I of the EF 35mm f/1.4 was purple fringing.
I believe I'm not the only photographer who associates lens choice with judgment and skill as a photographer. For me, camera lenses involve an emotional connection. We replace all kinds of appliances, vehicles, and tools in our age of extreme planned-obsolescence, but we aren't using many such purchase to express ourselves creatively.
The idea of dumbing down a 35mm L prime grates on me. I'd be sad to replace my current EF 35mm f/1.4L II treasure with the new version. And I doubt that Canon is going to have two-tiers in their L series for this lens.
But I'm not so freaked out that I'm going to spend money that may never get used. I don't believe I will be "crippled" as a photographer if I had "to settle" for the new VCM version. On the other hand, I fret over the trend of downgrading aspects of optical quality.
Also, I try to understand Canon's perspective, and I think I should be grateful that they are doing as well as they are in the age of smartphones and digital manipulation.
From what I've read lately in the CR forums, hard-nosed pragmatism drives the majority of purchase decisions, but some photographers are concerned about where the industry is headed with engineering.
when it comes to handling and ergonomics R5 is just perfect, although I loved the feel of the EOS R even more because size and weight are perfectly balanced (R5 is a bit too heavy imo). 
