At the moment there seems to be a compromise - not legally enshrined as I understand it but fairly well enshrined in practice, that you can ask people to remove face coverings in public places where security or identity matters. So for instance someone with a motorbike helmet walking into a bank, or a woman in a Niqab giving evidence in court.
As I understand it, the wearing of a Niqab is a religious decision to imitate one of the prophet's wives, not a requirement connected to the Islamic belief that both sexes should dress modestly, so requesting its removal is different from, say, telling women they can't wear burkinis to the beach.
For me, the acid test is "why is this making me uncomfortable?" If it's down to fairly arbitrary rules about what counts as modest/immodest (which all societies and cultures have, my own included - otherwise why would I feel uncomfortable about going topless on a beach in the S of France), then I should probably let it go.
But seeing people's faces is pretty fundamental to communication, and pretty much cross cultural (including among men in cultures where women go veiled), which is why I think the Niqab goes beyond arbitrary rules on modesty and into the realms of the dehumanising.
However, that's how I see it from outside - as a patriarchal rule whose purported explanation (immigration of one of the wives of the Prophet) is just a post hoc rationalisation. To a woman within a Western culture who has chosen this as a religious and political statement, my claims about "patriarchal post hoc rationalisation" probably come across as patronising.
However, so long as we sort the practical issues - that it's okay to expect her to unveil in a court of law, for instance - then I'm okay with her wearing it on the occasions where it doesn't matter, so long as she's okay with my freedom to express that I think it's a regressive choice.