How much longer can the US count on Japan to buy Treasuries?

The Shinsei-Aozora marriage has just been announced. Official announcement to be made some time in May (this month!) and the happy day is some time next summer (holding company structure). One wonders about the shotgun nature of this union (but if it is a shotgun, there's really no doubt who's holding it).

Surprisingly, given the howls of protest from within the LDP that greeted Suga Yoshihide's proposal to include a ban on hereditary candidates in the party's election manifesto, the LDP appears ready to include restrictions on political inheritances in the manifesto...