Reunification means that both side recognize that they're Chinese. Things like systems or ideology are not that important and can be worked out. They could have different governments. In fact a federation solution was proposed (and rejected) in the 80s.

Furthermore, the Chinese sense of history is much longer. There are many examples in Chinese history in which some territory splitted off and then reunified later. So things like "the configuration won't be stable" wouldn't be Chinese thinking. To the Chinese, splitting off is the unstable configuration.

Given how the current Taiwan situation came to be, many Chinese view the Taiwan government as relatives with whom they've had a fight, and whom — after losing — bunkered down in the basement. The basement is still part of the house. They're still part of the family, so let's not be too cruel to them and seek peace. But if they no longer claim to be part of the family, then kick them out.