Its not about trade. China will continue to trade with everyone. Its about strategic loyalties. When was the last time a country firmly changed its stance from pro-west to Pro-China/Russia, or even neutral to pro-China/Russia?Venezuela is a peanut in the Latin American political landscape and China has been doing fine for years dealing directly with Brazil, Mexico, and others. Likewise in the Middle East with China's dealings with Saudi Arabia, UAE, etc. The political destruction of Iran and Venezuela and conversion into puppet states is actually not significant for China. The biggest losers by far are the Venezuelan and Iranian people.
Instead the opposite has happened, countries that resisted western domination have been singled out, sanctioned, sometimes bombed, and eventually life has been made a living hell for its people. Its only a matter of time, but pretty much all these countries in this kind of hopeless scenario will admit defeat and likely have some kind of regime change towards the west. its just pragmatism.
So, what incentive is there for a new country to change its political stance and fight western domination? If its so costly and ultimately leads to defeat?
The example of Iran, venezuela, Cuba only makes other countries bow down to US and European domination. They get afraid and accept humiliation. This also negatively affects China as no country trusts China to be a strong backer. So, they listen to the order of US and the west when it comes to enforcing sanctions against China and Russia.
As China gets powerful, the west will force countries to choose sides and use these past example to threaten them to shun Chinese trade, investment or influence. China needs to start spending its money and resources to start backing up countries like Iran. It needs to stop being fence sitter. Cause otherwize, it will be truly isolated over time.