Well even if they crash they'll get to keep their consumables so its not all bad.
I did actually test that, for both equipment and consumables.
It turns out you don't actually get back anything that you've already used from your manifest, but you do get to refill your available consumables and equipment, as long as you have enough to replace them.
So if you had 6 medigel, 8 rockets, and 12 thermals and ops before the game, and you had 2 Warp ammo I, one of them equipped, and 1 Power Amp 1 which was equipped, and you used all 6 of all your consumables before the host migration, here's what would happen after the migration:
You'd have 0 medigel, 2 rockets, 6 thermal clips and 6 ops packs. You'd have Warp Ammo I equipped, but that's it (you wouldn't come back with Power Amp I equipped.)
When you finished the game, your consumable totals will have decreased by the total equipment/consumables used both before and after the host migration, so you would't have a Warp Ammo I left, because one was used before the migration, and the other was subtracted from your manifest during the migration, to refill your equipment slot.
I haven't tested it in many months, but it was after support stopped, so I'm pretty sure that's still how it works. In practical terms, it doesn't change much, unless you're like me, and perpetually low on Ops Packs. When I come back after a Host Migration, I often have less than 6 Ops Packs (I typically start most of my games with 6-10 of them, and will often use most of them, so that's why I noticed something was up, because they were the one consumable that wouldn't "refill" during a host migration.)