I agree with Zop in comic book terms, they can't do anything to each other.
Heck, Death and Oblivion would enjoy watching Abraxas be Abraxas, they kinda compliment each other.
How that would look in the end I can't say.
Death has her own realm outside of space-time, she's unaffected by all reality ending.
Oblivion, though unconscious at that point, goes on as well.
meh, Abraxas courts Death afterwards in that club for cosmics and they birth a new universe.
stoned ... But yea, raw power, Abraxas.