"However no matter how good the LCD is, the blacks are still quite inferior to plasmas."
This depends on the ambient brightness. Above a certain brightness, LCD has better black because it reflects very little ambient light, while plasma phosphors do. Below a certain ambient light level, plasma has better black for the same reason.
There is a level of ambient light at which a particular plasma will have identical black level to a particular LCD. For any two models side-by-side, this is called their Black Crossing. It is called this because if we superimpose their respective black level vs. ambient light graphs, the lines cross at a particular ambient light level. Specular reflection is not counted for this particular model, only phosphor reflectance.
At ambient light levels above the Black Crossing, the LCD will have better blacks; at levels below, the plasma will deliver the darkest blacks.
This Black Crossing is, for most (if not all) model combinations, well below the intensity of light in an average viewing environment.
Since market preference will form based on at best the average home viewing environment and at worst average purchase-location brightness (in-store decision), LCD has the black-level advantage.
An interesting experiment is to put an LCD and plasma display side by side, and send them both a fullscreen black signal. Then dim the ambient lighting until their blacks merge into identical inky pools. Congratulations, for you have now found their Black Crossing!