No, I don't think they're going to fight but I also think the idea of Aljo going to 145lbs is wolf tickets to talk himself up, outside of being handed a fight vs Volk for the 145lb title he isn't moving up and the only way he'd stay at 145 is if that matchup happened AND he won it.
If Merab thought he would be better suited for 125lbs or if that was even a reasonable option he would have probably done it already, the dude lost his first two fights in the UFC before grinding out this 8 fight win streak, he's 1 fight away from a 135lb title shot. He's not huge for the division but he looks pretty damn lean and dry when he's cutting to make 135lbs, dude competes at 149 for Sambo. Him going to 125lbs sounds like a croc of shit to me.
Aljo is one of the biggest guys so when they're side by side I can see why people think Merab is small, but he's a broad, thick guy with a big torso. They'll wait it out realistically, Merabs gotta win one more big fight still and Aljos going to have to defend twice successfully before this becomes a real issue...very good chance one of them losses by then. Here's Merab cutting before weighing in at 135lbs.