Riffing on an Observation by Warren Buffet

Warren Buffet, in his February 2008 letter to Berskhire Hathaway shareholders, points out that in the 20th century, the Dow rose from 66 to 11,497, or 5.3% compounded annually. If the Dow performs identically in the 21st century, it will close at around 2,000,000 on December 31, 2199. (Presumably en route to this sterling number, the "developing world" would literally have become another planet.)

Now, the Dow closed on December 31, 2008 at 8776, down 23.67% from the beginning of the century, or approximately -3.3% compounded annually. If we continue this rate, the Dow will close at 395 at the end of this century.

Which scenario has the higher likelihood?