For now, if you're a Canadian citizen, chances are you still will be able to get out. The problem is there are many.... For instance, there are some legislative council members in Hong Kong who gave up their Canadian citizenship status in order to run for election. I'm not sure how the Canadian government.... Whether or not we will regard them as Canadian citizens anymore is a question. Also, even if they are Canadian citizens, they may have family members who are not—either permanent residents or citizens of Hong Kong—so they may not choose to leave at this point, and it may become more difficult for them to leave in the future.
My other concern is that Canada may start to impose visa requirements on people from Hong Kong as well. Let's say you're a Canadian citizen living in Hong Kong, but you have family members in Hong Kong and you want to bring them with you to Canada. They may not be able to do so unless we have some requirements to allow them.
Right now, on top of everything else, there's also a travel ban, so unless you have family members who are a spouse and dependent children in Canada, you can't even come to Canada.
There are many layers of problems right now.