I don't see the point of f/11 lenses in anything other than extreme configurations - say, 1200mm primes and the like for birders, or relay lenses like the Laowa 24mm macro.
But the f/7.1 and f/8 zooms may have a place, even among high-end lenses. It all depends on their other characteristics - specifically, optical performance and maximum aperture at 400mm.
Currently, we have 100-400mm general-purpose telephotos. Sharp within that range and managing f/5.6 at 400mm, they're not wildlife or sports lenses (unlike the common perception) but general-purpose telephotos that work well for everything from landscapes, to portraits, to semi-macro shots, to the occasional wildlife or sports work on trips not dedicated to wildlife/sports photography.
If the f/7.1 or f/8 zooms can maintain this performance and achieve f/5.6 at 400mm, while extending the maximum focal length, they could do very well. Essentially, they'd be like the current 100-400 lenses, but with an inbuilt teleconverter to extend the range when needed. You'd still use a longer/faster lens for dedicated wildlife or field sports shooting, but this would add further versatility to am already-versatile type of lens.
Of course, all this is contingent on the lenses being sharp, well-corrected and with good bokeh - as good or better than the 100-400 lenses currently made by Canon and Sony (and the Sony one is among the sharpest out there) within that focal length range. But long lenses are relatively easy to design with large zoom ranges, unlike wider lenses.
So, if they're like 100-400s with extra capabilities, they could be great. But if they're slower at 400mm or optically compromised, they'd be little more than consumer lenses and a cheap way for low-end users to reach 500/600/700mm for a once-off holiday to East Africa or similar.