It's a challenging question.
I think at its core we're talking about people losing their political rights, having no access to a fair trial, being denied opportunities to political participation, and losing their very identity as a distinct community with a separate language and traditions. I do think those are valid concerns.
The motivations behind Beijing's policies in the two regions are somewhat different and have played out a bit differently. For example, in Xinjiang, obviously one of the issues that motivates the Chinese government is a desire to radically reimagine or limit or eradicate Islam. There isn't a comparable factor in Hong Kong. There is also the fact that we can still see what's happening in Hong Kong in a way that we can't in Xinjiang. There are still journalists, qualified barristers and lawyers there, and there is some space for civic activism, but it's diminishing quickly.
However, I wouldn't wait for the one to become the other to try to prevent these outcomes. I think Beijing has offered, even in just the last two or three years, ample evidence of its profound disdain...to gut human rights even in a place that is as internationally connected, as visible and as bound by international law as Hong Kong is.