Reading the article, they have a valid exscuse for why it might still be a 4MP ... erm I mean ultrapixel shooter.
"Why didn’t HTC make the One successor with a camera boasting more megapixels, and - very likely - higher level of resolved detail? We are just speculating here, but it’s possible that since HTC has had optics maker ST Microelectronics exclusively develop the 4-megapixel ST VD6869 2.0µm, 1/3-inch image sensor for the One, it also had to sign a longer-term deal for this exclusivity. This would have made “UltraPixel” a long-term bet for HTC, and regardless of the lukewarm camera reviews, the company might just not have been able to break that contract. Or the lack of a higher-pixel camera could be something totally unrelated, like the automated Highlights Reels that HTC is able to quickly and efficiently make with the smaller-sized 4-megapixel images."
So even if they wanted to, i doubt they could afford to get out of this deal. Still a deal breaker though. Silly HTC, putting all your microchips in one basket.