The important part of a boycott is not inherently to just bleed Blizzard of money. It is to make a statement regarding the issue at hand. By continuing to be vocal about it, more attention and pressure is put on Blizzard and other companies. A boycott is not "make them go bankrupt," it's "have them lose enough money until they change course."
It will also be important if enough key staff get fed up and leave. Without the creative people, ActiBlizz is just a bunch of shareholders. We know Blizzard employees are already unhappy with the situation because of covering up the sign saying "Every Voice Matters" at the Irvine office.
The bottom line is, the fearmongering that all these games will go out of business and employees will lose their jobs is ridiculous. People are making a statement. Will it work? We will see, but that's no reason to turn off the gas.
Tencent only owns 5% of Blizzard. It was entirely Blizzard's decision to preserve their large Chinese audience.