As we've mentioned in the other thread, HK's quarantine rules vis-à-vis the Mainland run until May 7, though they could easily enough be extended.
I strongly suspect that the Mainland authorities would like to see the border re-open for all sorts of rather obvious reasons, so a re-opening sometime in May along the lines you mention would not be a surprise at all. HK-Mainland-Taiwan-Macau could quickly become something of a free travel zone virus-wise, and I think Beijing would be very happy to see these areas united in this fashion.
There remains,though, the question whether foreigners would again be able to enter China, or whether the re-opening would only apply to those holding Chinese passports, HRPs, etc.
No problem from the HK side, since the restriction on entry of non-residents does not apply to those who've spent the past 14 days in the Mainland.
Last edited by 889; Apr 21, 2020 at 5:22 am