Even economists don't understand basic economy: Since there is a surplus of foreign US dollars, and the deficit is already too large, the last thing you want is foreign investment. It doesn't matter if it is in state bonds, real-estate or anything else, because revenue will go back to foreign nations any investment will build up the national deficit in an increased rate long term. (Unless foreign nations want US dollars to stay in the US economy; which is actually the same as just giving it away.)
Only a devaluation of the dollar with respect to local currencies will level of the deficit, and yes, the US may well be bankrupt. The latter is just in the eye of the beholder. If we want it to be bankrupt, it will be, and if we don't want it to be bankrupt, it won't be.
(Or foreign nations can just give money back, which we actually, just did. Devaluation or giving it back: it is all the same. In the end, the world is just trading their commodities with the US for green paper which must turn worthless since there isn't enough to buy back.)
