1. A massive asset bubble and a fundamental re-evaluation of risk/reward ratios for all investments. Historically, the average P/E ratio for S&P 500 companies is around 16. Roughly speaking, this means that investors are comfortable making their investment back in 16 years in static market conditions. Does this decision calculus change if you know that the Fed will bail you out as soon as times get tough? You bet it does. Similarly, corporations are much more incentivized to take on as much debt as possible in hopes of inflating their stock prices. When times are good, massive bonuses for execs all around. When times are bad...hey, bailout! I expect the "new normal" for P/E ratios to be in the 30-50 range. In the short term (next decade or so), this means the party continues, and we see massive growth in the stock market. But when the bubble pops, it'll pop harder than ever...
2. The second scenario is that debt-holders worldwide lose faith in the dollar and start dumping Treasuries, leading to hyperinflation. This doesn't seem to be happening as of today, in fact, the more money the Fed prints, the stronger the dollar. Central banks worldwide are printing money as well, so the dollar looks like the "least ugly" choice by comparison. The big unknown is how long the Fed can keep printing before debt-holders start second guessing the dollar's value.