But it isn't just the focal length, live sports requires certain ergonomics and the power zoom (handheld) or big box lens is the standard for a reason, they just work the way people want them to work. Even with a teleconvertor to make the image circle larger, I don't think these are a good fit to an s35 sensor. Most are going to be 8mm, 9.5mm, or maybe up to 10mm. You'd need to more than double the image circle to cover the sensor (a nice graphic here for sizes) https://www.cinema5d.com/fs5-fs7-b4-lens-combo-servo-zoom-4k-explained/
If you start with a 10mm x 100, you put a 2.5x teleconvertor on it to get it up to the size you need, and lose 2.5 (or more) stops of light (really rough amount). Now you have a 25mm (near normal focal length on S35) to a 2500mm tight lens. Plus if the lens doesn't resolve more than 8k worth of lines, once you blow it up you will have a lot worse resolution. The teleconverters ALWAYS reduce resolution, you are spreading the finest detail that the lens can resolve out over a bigger area, and then sampling it over a greater number of photosites in a finer pattern. The larger the conversion, the more the image degrades. Let's assume a 6um photosite size for the 4k lens, in order to keep the same resolution (assuming zero loss from the converter), you'd need 15um size photosites just to keep the 4k resolution. If the photosites were still 6um on the larger sensor, you would have multiple sites gathering the same line with a 3 for 2 scheme or about 3.4k to 3.8k effective real lines of resolution.
The above is gross approximation and gross exaggeration to get the point across. While this 8k sensor is a great achievement (don't forget this is global shutter too), I don't see this as being great for sports coverage in any way except as a handheld with a relatively short zoom like the ENG style Canon power zoom that is already on the market. We are really going to need lenses that can resolve this high, and are built for this size of sensor to really get the full benefit, and unless Canon or Fuji have something up their sleeve, this will leave out big box lenses like the 50x, 70x, and 100x sizes. The question then becomes, it is easier to design a lens for a small sensor or a big sensor image circle? If the big is easier, then modifying the big lenses might be an "easy" task.
If you start with a 10mm x 100, you put a 2.5x teleconvertor on it to get it up to the size you need, and lose 2.5 (or more) stops of light (really rough amount). Now you have a 25mm (near normal focal length on S35) to a 2500mm tight lens. Plus if the lens doesn't resolve more than 8k worth of lines, once you blow it up you will have a lot worse resolution. The teleconverters ALWAYS reduce resolution, you are spreading the finest detail that the lens can resolve out over a bigger area, and then sampling it over a greater number of photosites in a finer pattern. The larger the conversion, the more the image degrades. Let's assume a 6um photosite size for the 4k lens, in order to keep the same resolution (assuming zero loss from the converter), you'd need 15um size photosites just to keep the 4k resolution. If the photosites were still 6um on the larger sensor, you would have multiple sites gathering the same line with a 3 for 2 scheme or about 3.4k to 3.8k effective real lines of resolution.
The above is gross approximation and gross exaggeration to get the point across. While this 8k sensor is a great achievement (don't forget this is global shutter too), I don't see this as being great for sports coverage in any way except as a handheld with a relatively short zoom like the ENG style Canon power zoom that is already on the market. We are really going to need lenses that can resolve this high, and are built for this size of sensor to really get the full benefit, and unless Canon or Fuji have something up their sleeve, this will leave out big box lenses like the 50x, 70x, and 100x sizes. The question then becomes, it is easier to design a lens for a small sensor or a big sensor image circle? If the big is easier, then modifying the big lenses might be an "easy" task.