Sony is starting to get traction but people see big white as Canon so it might not work out too well for them. Sony's main issue will be that Canon and Nikon are coming out all guns with much better mount designs that are going to let them push out lenses that are better than before while also having a huge range of lenses to fall back on (including exotic lenses like the MPE-65, Tilt Shifts, and full ranges of super telephotos). Sony has some new lenses that git key areas but they still lack the ergonomics of a pro(pre gripped) body.
The A9II is a good camera and you can certainly see Sony has a head start in building mirrorless cameras and their sensors are really good, but they are competing against two giants that have just woken up and decided to throw everything and the kitchen sink at it.
Mirrorless seems strong for sports as you can face detect and little box lock-on AF your way to victory. But I don't think it is there for some forms of wildlife yet, I have spent a whole day peeping out the viewfinder to see if my target is there key and would not want to do that with a screen.
That's what I have been thinking, too, that someone at home watching a sports event on TV who sees a white lens isn't going to immediately discern the differences between one white lens and another, and since Canon is already noted for their white lenses will assume that the photographer is shooting with a big white Canon lens, when in fact it might actually be a big white Sony lens. I have now looked at photos of Canon lenses and Sony lenses and for someone who is paying attention and looking for specific details, it will be apparent which lens is made by which manufacturer, but....how many people are going to be interested in such specifics? Canon is still going to be the manufacturer most identified with white lenses. Time will tell how all this plays out....
I agree that mirrorless can be very strong for sports as more and more photographers discover and realize it, but it still may take some time yet. Ditto for shooting wildlife.
As a very long-time (over about 40 years, I think) Nikon shooter I was intensely disappointed in Nikon's lineup of lenses both at launch of their Z system and as time has gone on. I am particularly interested in macro and there was no macro lens to be seen and available (and still isn't). "Just use the FTZ adapter," has been Nikon's answer and that of many loyal Nikon shooters, but that is not the way I want to shoot. I much prefer native lenses. So, as a result I am now shooting with Sony gear and am very happy with it so far. The current lineup of Sony FE lenses meets my needs and wants and I have been more than satisfied with the lenses I have so far. Actually, this has been good for me, too, switching to an entirely different system, as it has really made me think carefully about the genuine value each new lens can add to my shooting style and desired results, and I'm finding that having a few lenses which really will get some use on a more-or-less regular basis as opposed to a whole bag full of some which rarely see the light of day for months, maybe even years on end, is a very good thing.
I absolutely adore my A7R IV -- definitely the right choice for me from Day 1! Haven't used an A9 II as I don't shoot that many situations where capturing fast action is needed -- BIF, sports, etc. -- but everything I have read about that camera body sounds as though it is indeed a gem.