The British tried holding on to HK. Thatcher adopted a hardline stand during the early negotiations because Britain just won in Falklands. Deng Xiaoping called her bluff. Without our military, you think the British would have given HK up willingly? No.
We can take over Taiwan anytime we want, but there is the matter of American intervention. We don't have the air or naval capability to match them yet, thus we're taking our time. I don't advocate for immediate invasion of Taiwan, but I do advocate tying economic incentives to unification process. You don't reward a child for behaving like a brat, so why would you give sweets to Taiwan if they are in bed with Americans?
Economically, Taiwan needs mainland China, not the other way around. If they want economic benefits, they will need to follow a time table for unification, not play the status quo game. Let's say at a certain time (20 years for now), they are still wishy-washy about unification, we take the island by force.