This relies on the assumption (possibly correct but I don't think definitively established) that a multi-polar world where e.g. China enjoys a similar status to the US would result in them imposing their own values on the world in a similar manner to how the US has done or deposing distant governments. So far China's interactions with the world outside its immediate vicinity (Taiwan, India, SCS countries) have largely been of an economic nature rather than the more bomb-dropping and CIA-flavoured approach the US has taken. So I don't think that the United States' relative loss of power necessarily means a worse world for those outside the US (again, excluding China's immediate neighbours).