I wouldn't lend a lot of credence, the only source is the quote from Tanaka. The article is also written in a pretty weird way:
Quote: A recent tweet from Kimio Tanaka (a Japanese photographer who has Ricoh/Pentax insider information and has a good record of reporting relevant information) indicated that the progress was made on the successor of the Pentax K-3 II camera
There is a big difference between "the progress was made" and "progress is
being made" - which seems to be the meaning behind Kimio Tanaka's tweet. On the comments, the author says regarding the sensor:
Quote: "That's right. It will probably feature 26MP (currently in latest Fuji gears) or the 32MP (EOS 90D) APS-c sensor
This, when Pentax has never sourced sensors from Canon (does
anyone even source sensors from Canon?)... I wouldn't really call this an authority on the subject.