This will definitely reek havoc on the global economy.
And you're probably right. Hong Kong's status made it home to a lot of the financial engineering of commerce between China and the west. With it losing its status, I think a lot of the financial machinery in HK is about to come undone. Singapore will likely benefit, to some degree, from this move. The world and China may need to find new markets and suppliers in the short term.
[0] All states with any influence in the matter, China and Hong Kong SAR