Or non-dollar denominated assets. Remember, Greenspan thought the market was overpriced, almost exactly 10 years ago, when the Dow was around 6400, the Nasdaq was about 1250 and the S&P 500 was about 740. Just because he sees a sinking dollar doesn't mean he's right.
Actually, he's a little late to the party. The dollar has been falling for years. But he's right about one thing. Given our massive deficits, coupled with our inability to compete with Red China's slave labor force, the dollar has no choice but to fall further (barring a massive rate hike by the FED and/or massive spending cuts by Congress).
True, as far as it goes. But I can't see the Euro or any other fiat doing better than the US. After all, when push comes to shove geopolitically, only the US is in a position to do any sustained shoving.
Some smaller currencies, such as the swissy or canuck might do better, but these are small markets that cannot possibly absorb the amount of buying interest that will be sparked by a continuing slide in the dollar, say below 80 on the index.
That said, diversification is always a wise plan.