Sure but the death of one or the other is the end state of the war.
Moreover, people are givng burgers less and less aid, something lefties ignore Zion Don complaining about. So while it would be 'world' in theory it would be overwhelmingly chinese and american people in the trenches, their cities being destroyed and their resources being consumed.
Once that front really becomes prominent and both sides invested, Rus would come out and start fucking with shit because they know security is low, which would require EU to counter force them and give less to the burgers. Mid east isn't really on board super hard with chinks or burgers so they'd take this as their best oppurtunity for uninterupted mischief as well. Whomever wins the main battle will rule the remaining side factions, assuming they aren't too weakened. Like as not they WILL be weakened so both China and America lose hegemon status.
Africa, Oceania and SEA get to laugh it off as the rest of the world chimps. There'd be losses but nothing on the same scale as the active participants.