Arbites dialogue makes regular Sororitas seem unlikely as the next class.
Changed my Arbitrator to Authoritarian today and noticed some dialogue between her and one of the Ogryns. She calls him "Dauntless" and even went out of her way to explain what that word means. As far as I can recall this is the only time during Darktide's dialogue that "Dauntless" is uttered and the whole conversation revolves around that specific word. Fatshark would not go out of their way to create dialogue centered entirely around a word and then use said word to refer to a new class if there was no connection. So how should this be interpreted? I see an obvious conclusion here.
According to the Authoritarian, Ogryns are dauntless.
According to Fatshark, the new class is dauntless.
It is only logical to therefore assume that the new class will be more Ogryns.
Of course dataminers have uncovered all kinds of Sororitas equipment already which narrows things done further and leaves only one possible option:
The new class will be a convent of sisters staffed entirely by female Ogryns, the Order of the Hungry Saint.