Black and White 2 actually had really solid sales in terms of DS games. They sold about 7.97 million units in total, despite being sold towards the end of the DS's life cycle. They have around the same sales numbers as Pokemon Platinum, which sold 7.69 million: it only sold slightly better than Platinum did. Despite this, it sold much less than BW1 and especially Diamond and Pearl, which sold 15.58 million (Black and White) and 18.23 million (Diamond and Pearl). It also sold less units than HeartGold and SoulSilver, which sold about 12.72 million units. XY and ORAS individually both have sold more units than BW2 have. BW2's sales were good, but they weren't much better in sales than director's cut games like Emerald/Platinum.
Pokemon Z would be a nice swansong for the 3DS considering the handheld has almost run its course, it would be good I guess. I'll remain silent on it until Nintendo says any official stuff about Pokemon Z soon enough in March/April/May. I'm expecting more of a third version here considering we have two paired versions and remakes, and the information about Zygarde that strongly points to a solitary Pokemon Z version. To be quite honest, I'm actually expecting a Pokemon Z this year considering that this is two years after ORAS was released, and every generation from 3 onwards has about a one year's gap between at least one pair of games (there was a year's gap between RS and FRLG, one between DP and Platinum, one between BW and BW2), so I'm thinking Z will come out as a grand finale to this gen. I'm sure this gen in general is playing huge honors to the Pokemon franchise as a whole, considering X and Y honor Kanto greatly and such. Oh and we're seeing Volcanion in a movie this year so...
On another note, I also do not trust the sentiments about a new console (NX) coming this year, let alone seeing a Zelda launch title on it. We've already heard about an upcoming Zelda game for some time now for the Wii U, and according to some reports its trailers say it's only on Wii U. Furthermore, if we were to see the NX this year or so, I'm sure Nintendo would be actively talking about it by now. They've chosen to remain silent about it, and they refuse to say anything regarding the mass rumors going on about it. They've only said that it's in development, and Nintendo has always started developing their consoles about two or three years after they release a console (the Wii started being conceived immediately after the GameCube hit the shelves). Plus I'm sure it still needs some time to get the software developed for it, because if Nintendo doesn't want to fall into the same pitfall that they did with the 3DS and Wii U, their launch lineup of games needs to be rock solid.
Plus even if they claim it's a Nintendo employee, we can't even trust that. We don't know if that employee in question was being honest or not, as he could have been lying either due to not really knowing what the higher-ups are up to, or purposely concealing the truth in lies in case they were asked about it due to the information regarding NX development possibly being considered confidential information. This is honestly possible considering that Nintendo has chosen to remain silent about the NX, and it's highly likely that at least some details regarding the console in question are confidential info.
Bottom line is, until Nintendo says anything, I think we should take all the sources at hand with a grain of salt regarding Pokemon Z or anything Nintendo has in mind for the future. I really will remain skeptical about all of this until Nintendo makes any official announcements regarding the details. Nothing is impossible, but I don't think anything is trustworthy until Nintendo makes any big announcements either at E3 (unlikely) or a Nintendo Direct.