In Hong Kong, Catalonia and Barcelona, Etc, Protests are happening. I am a Hongkonger, And I know what is going on through these months. The fact that protesters are frustrated to fight for their freedom, Along with the police forces, Which angry the protesters. If protests continue to occur and China decides to give up the city, It is likely they attack and destroy it. That would cause the US to attack China, North Korea to attack the US. . . The government would do something more inhumane to protesters in various cities, Needless to say, The harm of war. Russia will join China. European countries will be forced to choose their sides. Domestic mess is going to expand greatly.
There are no truly Signiant events taking place. Shure protests and the trade war seem significant but, They are not long lasting and can easily be put to an end. Russia making a grab for eastern Europe or china attacking Taiwan are just two of the far likelier causes for such a conflict
As much support as I have for the fight for democracy in Hong Kong, I don't believe it will lead to the beginning of a third world war when humanity as a species has too much at stake to even consider it. I certainly don't see the United States or the UK getting involved, At least not at this point in the struggle.
Who knows what the future holds, But there's currently no reason to assume the fight for liberty in Hong Kong will lead to another violent global conflict.