But Black and White aren't colors. They are the two ends of the color spectrum, but are not colors themselves. Black is the Absence of Color while White is the over abundance of all the color mixed.
(I know that is primarily used for light, but without light we wouldn't have color to begin with.)
Red and Green were the first colors released, later on Blue came into the picture. (odd relation seeing how Red, Green, and Blue are the three colors that our eyes pick up the easiest and use to merge into other colors {TV Screen Colors} while Yellow was an English replacement for the third for the first series, although technically the Fourth for Generation 1. Yellow, Red, and Blue are also Primaries.
Gen 2 is Precious Metal, but at the same time, Colors as well as Gold and Silver are colors. Crystal being a Gem stone.
Ruby, Sapphire, Emerald. Start of the new coding for Pokemon which caused a rift to form between the Generations 1 and 2 and all the future Generations to follow. Also Gem stones whose colors are Red, Blue, and Green (First Generation Irony?)
Diamond and Pearl are precious stones, while Platinum goes back into Metal. *reversal of Generation 2*
Now Black, absence of color and White, all colors combined. Though not technically colors themselves.
Really running out of names was never a concept as they basically recycled ideas since Gen 3. Black and White are a new step forward that broke away from the repeated cycle.
As for possible of Gen 6. We are still 5 years too early for that to even be considered. (Is guessing at ample time as since Gen 3, it took about a year or so for a third to appear and then two or so for the revamps, then another Year+ for a new generation to appear.)
I believe that Game Freak did state they were making an off brand for the Wii to compliment the new Black and White titles. Plus we still have side series to wait for such as a new Pokemon Mystery Dungeon or even Pokemon Ranger. Who knows we may even get a brand new side series altogether.
