Seriously, guys. Pokemon 6th gen isn't coming until 2014 Japan 2015 UK/US. Nintendo took a big decision when making B/W a DS game. It means no 3DS version for about four years. Pokemon is a brand, which means in order to protect that brand they only add new pokemon very occassionally - every three or four years. These 157 from B/W will last through several years of the cartoon series, 3 or 4 films, several sets of Pokemon cards and years of the competitive battling scene getting to grips with the new gen and the ins and outs of the new metagame. Pokemon is a special case, and from Pokemon's perspective, it cannot release a new gen for some time now.
From a console perspective, Pokemon sells. Shedloads. B/W could reach 20 million lifetime because it's launched on a console with about 140 million sold. Why release that on a console with 4 million by year's end, max, and cut off the rest of the sales?
A 3DS Pokemon will likely launch to about 30-40million machines if it releases in 2014; which will let the series get the kind of sales it always gets (10-20 mil).
All of this is not to say we wont see Pokemon Grey or R/S Remakes coming to 3DS before then, though. These side-games usually make 5-10 mill and so can release earlier in 3DS' life. But even then, I wouldn't bet on it.