Why would they want to do that? I would bet lots of people will revolt, forcing them to drive on the wrong side of the road.
At this rate, they might as well force all the people in HK to Speak Mandarin, Write in Simplified Chinese. Or get rid of them all together if they don't comply. Oh there is a word for it, Genocide.
The taxis, logistics and trucking industries do have political clout, though, and they will be the ones pushing back.