I've seen that linked to document, but it says "This document aims to provide background information regarding the intergovernmental agreement (“IGA”) to be signed between Hong Kong and the US for implementation of the US Foreign Account Tax Compliance Act (“FATCA”)." and "Information provided in this document will be updated according to the development regarding the signing of the IGA." So it says "to be signed".
However, after looking further I see at https://www.fstb.gov.hk/fsb/topical/doc/HK-USIGA.pdf it appears that it was signed and other websites said there is an exemption for MPF accounts. However, as TVC accounts are a new thing and aren't mandatory I guess it still remains unclear how they'll work for Americans.
I like balancedequatio agree that "the bottom line for me is that it's still better than being initially taxed on the income by the HK government" I'm not sure how annoying it will be with reporting and/or declarations, but I've done my best to attempt to comply with FACTA since I've been living and working in HK. I will continue to tell them (IRS and the Treasury) my whole non-US financial story, which is so annoying and almost no other countries require. How the US can pass a law within their borders and make the whole (or at least most) of the entire financial world follow their law is ridiculous.