Based on my assumptions, Bakugan toys are no longer sold in stores. You can still purchase them online, such as Amazon, but it would be difficult to afford authentic ones since it's now "rare". You would most likely come across knock-off Bakugan, and if you see any expensive versions, then they have a good probability of being genuine since it's no longer being produced.
As for the anime, I can't be so sure if Bakugan: Mechtanium Surge had an established conclusion to the entire series. It certainly ended ambiguously, and to answer your question, the franchise is no longer popular as it used to be years ago. But fortunately, Sega is planning to reboot the series. We don't know how it's going to turn out, but let's hope it's better than before.
To answer your question, Bakugan is no longer a "thing" in 2016 so far. But the franchise will make a comeback soon.