I personally would love to see something like this added, it would add a bit more flavour to the far north of Skyrim with a unique regional enemy. I also have a few ideas in regards to these creatures. They could be more powerful than the standard Draugr you find in the rest of skyrim. They could raise the dead, have really powerful frost spells and immunities, They could have powerful shielding spells like Ebony skin, summon frost Atronachs and be in the company of Ice Wraiths. If the Dragonborn DLC is used to make this mod, you could even make them climb out of the snowy ground just as the Ash Spawn climb out of ash piles on Solsteim. Also like the Ash spawn, you could give them unique looking frost weapons that do a lot of damage. I think when they are killed, they should turn into a pile of ice just like frost Atronachs and Ice Wraiths. I also think the further from the roads and civilization you get, the more powerful and numerous they become and areas you encounter them should have either no or very little wildlife in the vicinity of their spawn points, which implies they've either killed everything or all the creatures have fled the area. You could also make some really cool (No pun intended), frost themed dungeons to fight them in as well. You could really make the northern wastes of Skyrim a very dangerous place to be with these new enemies and i think it would not only be kinda lore friendly, but also very fun and challenging to play.