They will continue to sell to both , the difference being that the dollar will no longer be accepted in trade , we will have to buy their currency or trade with gold , etc , or they will accept the dollar at an extremely devalued rate ( think Weimar republic ) but it will continue . That will effectively knock us out of the world policeman game , which will actually be doing us a favor . I would bet they have things like that figured out , thats what economic coalitions are for , we have put ourselves in the position that we MUST continue to buy things from them , no matter our troubles at home , because we dont make anything domestically of any quantity , or consequence , we make good bombs ………..but no money for defense spending shuts that down as well . Economics aside , China is a Communist nation , they are slowly shifting away from that towards socialism , but the old guard may wish that the change moves more slowly , crashing us , and slowing their trade would accomplish that internally . Russia doesnt really need us for anything , India , I have no clue about how they fit into the BRICS coalition , South Africa and Brazil are both 3rd world nations with good natural resources , they would notice little change in a western crash . 3rd world is 3rd world , poor is poor . If you look at the alliances that have been made , they could easily weather out the storm on their own , while they wait for the west to scramble around and restructure .