Let's assume the worst case scenario and the game is not available in HK psn store (though I don't see any reason why it shouldn't on 16th), you still don't need to import physical discs from US/UK. All you will need to do is create another psn account on your PS4 for the region from which you want to purchase the game - say US in this case. Create a US psn account. Then purchase a digital US PSN card from a web site which sends you the code within a few seconds. There are plenty of reliable sites which do so if you search on google. Then you go yo your US psn account, load up your wallet with the card you purchased (by inputting the code you received via email) and simply head to the psn store and purchase the game. Done.
I've done this thing often and it literally takes a few mins to complete this process. I know of people who have US, UK and Japanese psn accounts as some games are often available in Japanese or European/UK psn store but not in US one and vice versa. Google is your friend and this is way simpler than importing the game physically from a different region.
