Old wine in a new bottle (MF vs. FF question)

The new bottle here is my specific context.

Hi. I photograph everything as a hobby. About every three years or so, I evaluate my gear and add/replace stuff as needed. I am at a similar crossroads today with a difference. I expect this to be my last system decision. After I retire in a couple of years, I won't be spending anymore on camera gear.

I want to briefly explain my current situation and ask you if you agree with my evaluation.

I am posting the question in this forum because I have a desire for MF camera, but all my evaluation tells me it is not the right choice for me. Also, there is no single forum for FF cameras; I'd have to post it on Nikon/Sony/Canon forum. And many members here do use FF systems.

Background:

For my majority use case (dance events, mostly under stage lighting) I use two M43 bodies paired with Olympus 12-40/2.8 PRO and 40-150/2.8 PRO lenses. One of these bodies with Panasonic Leica 100-400 covers suburban wildlife. The two bodies and two lenses (unmounted) fit into a shoulder bag. The convenience of F/2.8 zooms and the size of M43 system were the decided criteria in building this system over last three years. The seasonal/open box discounts also made them very affordable. I spent last three years building this system and it is now stable.

For everything else (travel, family, nature, landscapes, etc.) I have been using DSLRs for 20+ years (starting with XTi, then D7100, D7200, and D810).

This week, I am getting rid of all my DSLR gear. I kept them a bit longer than I should have because I had to get used to ML cameras, get the confidence that they can do the job, etc. Once I got that confidence, my DSLRs are being used less and less. So, the timing is right.

Future plan:

I am not interested in APSC cameras because there is minimal benefit over M43, not worth maintaining a second system. FF offers around 2x dimensions (4x sensor area), while MF is even larger.

I am considering a hi-res MF or FF body (50S II, Z7 II/successor, A7RV, or S1R/successor). Only the A7RV in this list can be called new or recent while the other three are rumored to be retired or replaced with new versions.

What I need is best IQ on budget around three focal lengths... 18 to 20mm for landscapes, 35 to 40mm for general/people/street/travel, and 75 to 85mm for portraits. I am hoping for a three-prime kit.
[This thinking largely evolved from another evaluation I did with my friend, a Sony shooter, for his FF A7RV]

While a FF body will offer me a lot more choice of longer focal lengths, I don't have appetite for their cost or weight. My M43 bodies with tele zooms will do that work.

Evaluating MF:

My idea is to get the lowest cost body available today. This is where the 50S II is appealing. With rumors that there will be no more 50MP MF cameras, the 50S II is the cheapest MF camera available new. Same can be said of Z7 II.

It will allow me to buy the necessary lenses over next two years or so. After that I can think of replacing the body with then current model. This goes against the retirement comment above, but I'll have to see what body is available in three years and how affordable it is. Buying a better body today will make buying lenses difficult (budget-wise).

The question I asked myself was, what could the new camera do beyond what the D810 could?

1. I do not have any expensive lenses that could use the full potential of D810. I did not want to buy DSLR lenses in the last few years as the industry is moving to ML cameras. One factor in the ML cameras I am finding on ML is their rear screen, which on my DSLRs are fixed, non-touch enabled. I am also able to connect my M43 cameras to laptop (both USB-C) and download photos on the road, while DSLRs need card readers and cables. Both these cameras charge directly from available USB-C chargers (of course, my DSLR with a spare battery can go for a month-long trip without charging). This is a DSLR vs. ML debate, whatever the model. I feel I have moved on from DSLRs.

2. I have seen real-life results from higher res ML cameras. When used with comparable F/1.8 primes, the portraits from the higher-res ML bodies looked better to me. Many say that 36MP to 42 or 45 is not significant. However, this higher resolution and rendering (new sensors and lenses) look better on the same Dell-calibrated 4K monitor. This could be a personal preference but when I use both cameras at an event, I am liking the ML photos more than the DSLR photos. Both have similar pixel count, both shot with f/2.8 zooms under artificial/stage lighting. I could say the same of nature photos. I also know that colors can be adjusted in PP but that moves lot of time from photographing to editing.

3. The size of D810 with 24-70/2.8 lens bothered me a lot in recent years. I am hoping for something like Z7 II size. This puts the 50S II in the same category as D810 and therefore not desirable.

4. I am not a manual focus person. The AF coverage on the D810 is around the center. It has full coverage if using in DX crop mode. I prefer entire frame coverage. 50S II is similar in terms of focus points near the center, but there are more AF points than in D810. Other FF bodies have advantage in frame coverage.

5. The image quality of a MF camera is definitely a plus. Especially when shooting with good lens and taking the time for deliberate photography (unlike the run-and-gun shooting at events), the IQ potential is there. Portrait rendering and background separation are better due to larger sensor.

Bottomline:

I was thinking that there is a small window of opportunity to decide on the 50S II while it is available. However, with my criteria, it appears that a smaller FF body with fast primes is what I need. Both Sony and Nikon FF cameras fit the bill. The ISO 64 capabilities on Z7 II will be helpful for landscapes.

Do you agree or are there any points I missed about 50S II?

Thanks!