Sadly, the J in the model number is a dead giveaway that the Butterfly sequel is being primed for Japan. This could also explain why HTC decided to leave the 4MP UltraPixel camera at home and pack a 13MP sensor for Japan - megapixel count is rather important for Japanese customers.
If the Butterfly 2 is for real, it's interesting how HTC has chosen to approach its design - will it be a spin on the HTC One and (M8)'s metal armor, or something different? It's too early to know and, unfortunately, we can only speculate whether the Butterfly 2 will reach the US market in some form, while Europe is pretty much a no-go - the original Butterfly never landed there.
Thanks for the tip!