This is how Tool has worked since pre Lateralus. It takes Adam and Justin ages to finish a song and they do all of the writing besides the lyrics, and you can't write lyrics and melodies without the music.
They've had the album written for about a year or longer now and have been recording it since last April/May. Danny and Justin have had their parts tracked since around August and Adam has been tracking since then. Adam hasn't confirmed whether or not he's done tracking, but it's pretty safe to speculate going by his instagram posts and stories that he is and that they're now working on the mixing and mastering part of the recording process. Maynard has already been on record saying that 2019 will be the year for the new album and he's always avoided and dodged saying anything about the album before that. Unless Adam decides to say fuck you to everybody, it's coming out this year.