Excellent shots, I can see the sharpness (especially compared with your LM 24 shots on Flickr). Sharpness is very difficult to get past (IMO), once seen you crave for it all the time, its one of the reasons why I was happy to chop in a lot of my Fuji gear for the Leica Q3. A lot of motorsport sharpness coming from decent panning techinique, something which I often lack, I have short periods where I get in the zone and nail it, and other periods where quite frankly I'm hopeless. But nailing it witha sharp less makes the whole thing worth it
I only have the 50-140 and 100-400 and I could see myself losing the 100-400 for the XF200mm (+TC) but I couldn't get rid of the 50-140 as well, quite a lot of what I shoot is at close range (hillclimbs, infield at Oulton) and 200 would be too long. Then only selling the 100-400 doesn't put much of dent in an XF200mm price!!
I'm tempted to get one for an event on the free 48hr hire offer (though there is a £2750 deposit to put down!!)
In your shoes its a very difficult shout, because I would also be considering X-T4 -> X-H2S, and realistically thats about a £1000 (at least) upgrade once you take into account a CF-Express Card. I have found the X-H2S a big step up from the X-T3 (from the blackout free, the fact that I can use ES all the time with no artefacts, and the AF speed) - of course mentioning that doesn't help you!!
Credit Card Blanace Transfer to another card with 0% or very low interest period might help..........