I’m honestly not sure where the slow-trap will shine in Meltdown, if anywhere. None of the Meltdown maps really work well for Ghalt’s hook - the wide lane in Outskirts is his best bet. The others are all choked up with minions, terrain, sunspots, rifts, the usual mess. Traps also tend to get blasted away in the tight lanes, which are usually little corridors of AE death.
I see some Ghalts putting their traps in key Meltdown chokepoints (like the passage from supply beside the first grinder in Coldsnap, or in the tunnels to the basement shard in Outskirts). This is only going to be a minor irritation now, because a slowed character with an escape ability will be able to use it. Certainly not worth giving up a team spot that could have been taken by a wave clear character.
Hard to see what Ghalt’s role in Meltdown will be anymore. Character who are weak without team support tend to struggle more in Meltdown, I find, because it’s common to end up going 1v1, 1v2, or 2v2 in lanes. That’s why Ambra is the ultimate Meltdown support whereas Miko is a bit of a dead weight.