Angular response is an issue in sensor design that is considered by current manufacturers, just not on the extreme scale we see tech wides require.
Smaller pixel pitch makes pixels deeper (relatively speaking) which narrows down angular response. BSI makes pixels shallower, but what will that be used for? Maybe to make pixels even smaller while maintaining the angular response of today.
I had hoped that BSI would greatly increase angular response as a side effect, but the A7r-II results I've heard about (have not got test files personally) has not made me hopeful. I am a bit surprised that it haven't shown better results though, I was expecting more. It would be interesting to know why it fails to drastically increase angular response. Or maybe the angular response is good, but the microlenses introduce crosstalk over some critical angle? There's still no light shielding there.
I don't know if we really need to drop down to 60MP to get some decent angular response again, what probably is needed is that Sony's sensor designers get a different design target. I don't think their design target is "make as wide angular response as possible with current technology", but rather like "there's no need to have wider angular response than X degrees" and they design the pixel for that, which probably means a certain shape of the microlenses, no need for light shields etc.
I'm quite confident that they already have the toolbox required to do something better than Kodak did ten years ago, and do it with a smaller pixel size, but the demand for that is just not there in today's market. A manufacturer must want it.
More pixels, more DR, better ISO, video. That's what the larger market wants.
I don't think it's likely that Rodenstock will make a new wide angle lens line to fully support Sony's sensors. This is what you get, take it or leave it. More likely is that we get a medium format mirrorless from Hassy and/or Phase One, like a big A7r with a flange distance not as short as tech cams but shorter than the MF-DSLRs, and new wide angle lenses for that will be the future high-end king. By then resolution will be so high that movements will be done in post-processing, keep camera level and just crop, or tilt the camera and keystone correct. Lens tilt? Focus stack instead, automatic in the body like already on the XF.
I think classic tech cam and "large format style" photography could be commercially successful into the future though, but the manufacturers would need some Leica M thinking. Market it as a simple classic, support it with proper digital hardware. Tech cams has got stuck in market for the rational professional, where all is about technical performance and efficiency in workflow. When it's not as efficient or excel as much technically any longer, it fades away.