How many years will it take before Harlem becomes completely, or even just mostly gentrified?

Question

I live in the Upper West Side of Manhattan where the average brownstone, before renovations, will run you around 4-5 million dollars. I've noticed a trend towards a gentrification of Harlem as middle-class (for New York) couples move north in order to find more affordable brownstones in Manhattan and luxury condos are built by developers. Considering this trend, how long do you think it will take before Harlem looks like the Upper West Side?

Answer 1

Before this mortgage crunch I would have said two years.  But with homes not selling and Jumbo Mortgages a thing of the past, not for 10 years.