My interpretation of who is who, from top left to bottom right:
Loremaster = Azazel (an obvious reverse of her situation of being the only angel in Hell in the game)
Subject 67 = either a cameo, or the equivalent of the game's skeletons (although that wouldn't fit with the Heaventaker theme)
Dark skinned angel = Judgment
Triplet dog girls = Cerberus
Angel with the lollipop = Zdrada (the lollipop being a counterpart to Zdrada's cigarette)
Angel reading a book = Malina (her bangs between the eyes is a dead giveaway)
Long-haired angel with the crop and dress uniform with gold epaulets = Lucifer (she has the more pimped out uniform, and her hairstyle is the same)
Nun angel = Modeus (as a funny reversal of Modeus being a sex-crazed demon dressing conservatively and with a hopeless romantic hidden depth vs Angel nun who looks all proper at a first glance, then you notice her cleavage and exposed tights which implies that she's actually very naughty)
Sleeping angel with glasses = Pandemonica, obviously
Angel with the cap and long hair = Beelzebuth, by process of elimination, she has the second most bling uniform (befitting her status as the only other elder demon in HT) also the pentagram on her uniform is probably a reference to the way to unlock her ending in HT)
I just realized that in this hypothetical continuity, the Heaventaker disappearing would instead lead to a chain of events that would lead to the demon Azazel ascending and taking over Heaven!
EDIT: And of course the demon would have an Apple device...
This Heaventaker probably acts like a stereotypical nineties action hero, ala Duke Nukem or even Johnny Bravo, but in reality is real nice. He just has a gruff way of going about things in contrast with Helltaker who is more blunt and straightforward.