I'm pretty adamant that it won't. I mean, I haven't seen the storyline or anything but so far it's been the best pokemon game to date, as I quite like the style. However, if it were to just be a can of snakes and the first glimpse was just a tease from what I thought it may have been like, I will be dissapointed.
Gen one to four have been great and I think that pokemon has improved as the years have rolled on. I feel that B&W is the result of Gamefreak and pokemon maturing somewhat. If it turns out to be a failure I'll probably lose hope until something new or better comes out, which will happen most likely. Personally I hope they go onto a bigger console with the RPG's, something like the Wii or Gamecube. If Gen V sucks, well no biggie but I will be dissapointed, but I very much doubt that the series will ever have a bad game; at least in this line, spinn-offs are a diffrerent story.