Recently, Ian Hill says that there's no reason why Priest can't continue making albums.
Glenn will be in the studio writing songs, but without him on the stage is not the same. Maybe they will replace Andy Sneap after the tour. Or they can bring back K.K. for the next album tour (but with his recent interviews, I doubt). I hope for a great surprises in the second leg of the current tour in 2019 (50 anniversary of the band).
But if they can make a masterpieces like Firepower, I'm in for more album/s. Take 2 years break again, and create the same fucking great album. It will be a hard task for them to top this album, for sure.