There's a picture in the paper today of Trump wearing a mask. Will people who refused to wear masks now agree to wear them?

Most will not because Trump gave a reason for wearing a mask in a hospital , not anywhere else. 

In the English-speaking Western world, where we've been told different messages by governments and/or thought wearing a mask would make us look 'ugly'; think of Mr Trumps attitude in the beginning, his ego couldn't stand it - like any 'John Smith' (be he from Birmingham Ala., or WM.). I'm sure there are people on the Left who would have felt uncomfortable also, but look at how the West have dealt with 'masks'.

I think there will be just as many start wearing a mask because Trump is as there will be those who stop wearing a mask for the very same reason.

Many people are followers. Look at the toilet paper thing or politics. Some people will follow.