Are you saying the rest of the world should have stood up for what ultimately is colonialism? And colonialism of the British out of all the people? And also in a territory, that is directly on or neighboring the Chinese landmass? The Chinese people have a long history of others trying to conquer them or colonize them. They are probably pretty allergic to such notions, and will reject them. Realistically speaking, no one would have had the resources to force HK staying the same enclave it has been. This all sounds rather unrealistic.

We can agree on the treatment of HK being far from ideal, and I would go as far as saying, that even economically for China itself, it was not good to handle the matter as they did. That is where their ideology shows. HK was an economical hub. In recent times though many businesses left and more are unwilling to invest. This is the economical downside, that could simply have been avoided by not doing what they did. The question should be asked "Why not just leave it as it is, since it is working well, economically?" But they had to mess with it. Another downside is international reputation damage of course. China has achieved many great things in the past decades and now has cities more modern and convenient than most of what you find in Europe. Their one problem remains ideology. That they sometimes feel the need to do things, that are not economically sound, for the sake of ideology.

However, I can't agree with anyone arguing, that HK should not be part of China, like some people do in the comments here. It's a separate matter from policies implemented. Of course I wish for HKers to keep their freedoms. Who doesn't. Of course I wish China would not implement policies, that endanger the freedom of its people. But territorial? Nope, HK always was bound to become a part of China.

What I can say more from visiting HK twice is, that they still got Internet (uncensored), in contrast to other parts of China. Every week I am speaking with someone from HK, using Signal, which is not practical for anyone from (most?) other parts of China. When traveling in China, I used a HK eSIM, to have reliable and uncensored Internet. I hope that these aspects still remain intact for a long time, or that the rest of China will open up. At some point they should have the confidence in their own economy to compete on global scale.