This is a strange time to be thinking of this, with Thanos Imperative a half-year in the rearview mirror, but do you think there's an Avatar of Life or Death in the Marvel Universe right now?
Adam Magus/Warlock is dead (for now). Drax the Destroyer is dead. Phyla-Vell is dead. Thanos is. . . well, not dead, since he can't die, but trapped within a collapsed universe that is itself, dead. Thus, he's not in the Marvel Universe right now. Until some writer decides they want him, then he will be. That did seem like a dismissal notice Death gave him, though.
That takes care of all the characters holding those roles recently. It could be there's no need for one right now. Things were thrown out of whack when Drax killed Thanos in Annihilation, but Thanos subsequently returned, then killed his successor and Drax, before getting stuck elsewhere. Things could be back in balance and Death and Life have retreated to their corners, so to speak. It could be they only select a representative when they actually need one, because the balance is shifting against them, or because they want to make a power play. After the nearly disastrous intrusion from the Cancerverse, everyone wants peace and quiet for awhile.
Still, for kicks, let's consider some options. Maelstrom acted as a manipulator in service of Death (or Oblivion, which I'm guessing is both the same and different). Thanos was brought back, why not Maelstrom? Annihilus (or his offspring, I don't know how Hickman presented it) is up and running. He's in the Negative Zone, but I doubt it's hard to convince him to swing back into the Marvel U. to cause trouble. Death could always go big, draft someone like Galactus or Ego, but bringing in entities on that level might make things awkward with other Abstract Representations.
Magus said the Phoenix Force served as Avatar of Death at some point, which seems strange. I thought Phoenix' job was to keep the neutron galaxy in the M'Kraan Crystal from destroying the universe, which seems like Avatar of Life stuff. I guess he meant when it went Dark Phoenix and destroyed a star system. It abandoned Rachel Grey, maybe to join Hope Summers, maybe it ran to Jean's corpse for the inevitable resurrection, I don't know. I gave up on the X-Men years ago. But sure, why not Hope? All those folks who thought Bishop was crazy for trying to kill her sure will be embarrassed! Or she could be the Avatar of Life. Keep it ambiguous, but the X-Men (and all sorts of abstract Entities) are trying to jerk her one way or the other. Or maybe Hope for Life, Franklin Richards and his reality-altering powers for Death. You can't tell me there aren't entities that would love to use his powers for their own ends.
I was going to suggest one of those "Worthy" from Fear Itself, but they'd be better choices for an Avatar of Life. They gain strength from people's fear. Henry Fonda (in Once Upon a Time in the West) may have been right when he said 'people scare better when they're dying', but I imagine if they're dead, the fear goes with them, and so, the power. So, Avatar of Life. They might seem scary, but Drax was an Avatar of Life. Adam Warlock was the one who seemed to approach it more as helping and inspiring people, or patching holes in the fabric of space-time. Drax settled on destroying what was going to kill people before it could kill them.
If Life wants a slightly less crazy representative (or one that doesn't already serve another master), maybe Quasar. He's the Protector of the Universe, which he seems to regard as protecting life. He and Maelstrom used to tangle. I was going to suggest the Silver Surfer, after he defended the Wraith Queen and encouraged the Annihilators to bring Wraithworld back from Limbo, but there's the whole "serves another master" issue.
Maybe Moondragon? Her father served Life, so did Adam Warlock, who was a friend. She's not quite like either of them (she takes a wider view than her father, a more cynical one than Adam Warlock) so she'd do things differently. She was possessed by the Dragon of the Moon, a servant of Oblivion, so her representing Life might be interesting. Plus, Phyla became Avatar of Death to save Heather (good intentions, bad idea), but Heather's already seen how nuts people who worship life can be (her run-ins with the Universal Church of Truth) so she might have misgivings, especially if she was chosen, rather than choosing. It could happen. These Abstract Entities don't show much respect for the mortals who carry their water.
If they could actually use him, Rom might not be a bad choice. Given how he'd occasionally flip out and start murdering Wraiths, he'd be more of a Drax-type, but that's fine. Not currently an option, and I don't think Ikon's shown enough yet to take the role in his stead.
I guess they could go really off the wall, pick Daredevil. He's a lawyer, defending people so they don't spend their lives in prison (or get executed). Protecting life, plus he's run up against an Elder of the Universe and Mephisto, so he's done the cosmic scene before. He started questioning his sanity shortly after the Mephisto thing, then started being Bullseye, which isn't encouraging, but maybe he has a better handle on it now.
OK fine, forget Daredevil. Just have him fight ninjas in an dark alley while his girlfriend dies again. We'll go with Hellcat instead. Patsy Walker's adjusted to the weird, horrific stuff in her life a lot better than Murdock has. She even has vaguely-defined magic powers. Those should come in handy.
No rush, I suppose. Nothing much is happening now, but I imagine Life and Death will need someone in the future. Doesn't hurt to start considering the options now.