Three things will happen.
1)Some smokers will give up.
2)Some smokers will just leave the premises have a smoke and then return.
3)Some smokers will just drink and smoke at home more often.If they do it often enough some bars may see a little less turnover unless they can attract more non smokers.
The world will not end however.
Mind if they target alcohol next I wonder how many of our rabid anti-smokers will put up with that?
Frankly I can't wait to see the end of TB's government because I'm sick of the total bluddy nagging about what we do,ingest,exercise,weigh.Who needs a second mother?At least she only nags about what you wear and whom you see.