If china sees an opportunity they will take back not just vladivostok but also mongolia and siberia.
Look at the end of the day these powers will cut deals and partition/take back territory or carve out influence. There shouldnt be surprise if china has a deal with US that it will get some part of russian territory for keeping quiet or helping them. More or less china is aping west and wants to become like west, these kind of event taking place cannot be ruled out.
None of these countries are capable of trusting each other. And China defintiely wants to look much bigger on a map. They want their own Greater East Asia Co-Prosperity Sphere.