World GDP is $80T. An important fact: USD is world reserve currency. So no, I don't think that injecting, $6T is going to be super big deal. Just like in 2008, this additional money gets dispersed in to world economy or in other words the burden of US action gets transferred to other countries. This is precisely the reason why $2T injection has almost no effect on inflation within US but if any other country had dared to inject same proportion, it would have faced about 10% inflation making most of the imports pretty expensive for them.