I believe they can keep it propped up like they have...for decades. As we saw in the U.S housing crash, they have the wonderful ability to keep things going after a bust. They only need to create more growth and that is coming from debt. The nice part of that, for them, is they can create unlimited debt.
Yeah, but even this has limits. Quantitative Easing can be effective, as long as most people don’t look at that man behind the curtain. But once they do, they’ll start losing confidence in the currency. At that point, “the full faith and credit of the United States” will start to look like a Potemkin village.
FWIW, I think that the Fed barely pulled it off last time. Maybe they can pull it off one more time. I very much doubt anything beyond that.