Of course Taiwan economic dependence on China does matter a lot. The reason why most Chinese still believe they can reunify peacefully with Taiwan is because of Taiwan economic interdepence with China, which in the long term, hopefully will evolve into dependence. The day China leadership stop believing that, is the day they prepare for reunification through forcefull measure. If Taiwan can find a way to decouple from China economically, I think it will rudely awaken the Chinese leadership from their dream.
The US today is far different than the US in the past. Few years ago, nobody can predict that the US will launch a mutually assured destruction called trade war. Today, the relationship between China and the US is so bad, that you won't even recognized them anymore. With this kind of relationship, who can guarantee the US won't arm the taiwanese to the teeth like they are discussing currently? Of course the US don't want to go to war with China, but the US will love to fight China to the last taiwanese, japanese and australians. If the US start arming taiwanese in much bigger way than in the past, what will China do? If China tolerate the US changing the status quo slice by slice, it is only a matter of time before the US start delivering destructive weapons to the taiwanese. We need red line, and pelosi's visit could be just a start to test the water, to test the resolve of the Chinese.