I go to cafes mostly to work with a laptop. And I noticed that these days around half of the customers there do the same. I like the social atmosphere there and the change of environment compared to home. However, the noise might sometimes be the main drawback.
One workaround is to put on some music through the headphones, but music is not always desired while working, sometimes you just want silence. It would be nice if you could isolate yourself in a proposed private chamber which would be silent, but transparent so that you wouldn't feel totally isolated from the people and the environment, you could look around, have eye contact with people, smile, etc.
I think such chambers would also be useful for people who come to cafes to have conversations about sensitive topics, e.g. someone just broke up with their partner and a friend is comforting them and they don't want other people being able to hear this. Also, they would be useful for some business meetings. In fact, one could think of many scenarios where such chambers are useful and I think people would use them quite often.
Modern buildings in big cities often have a lot of glass in their architecture. Cafes often get established on the ground floor of large office buildings and have huge windows with a nice view outside. This is convenient for making such transparent chambers, they could be made along those outside-facing glass walls, that way you'd only need to make many transparent partitions and the "isolated" customers would enjoy the nice view outside as well as be able to see everything inside. The people sitting further in, away from the outside walls, would also still be able to see the outside view to an extent.
Transparent soundproofing insulation is not hard to make, modern windows are essentially that, the vacuum between the glasses serves the insulating function. Also, rather average insulation would be enough in this case. The only complication is that such multi-layered windows that a soundproof chamber would be made of would have to be rather huge to create the feeling of spaciousness, dividing a huge window into sections kills that vibe and you feel way more enclosed.
To justify the price for making such chambers, they could be reserved in advance for an additional price by people who anticipate working/having private conversations inside them. This would be very similar to reserving tables in restaurants. Those chambers that would not get reserved could be used by any customer of the cafe until they got reserved or rather until the time of the arrival of a reserving guest approached.