I vaguely remember someone here mentioning about these rats, but I cannot find it now.
These kinda look like cranium rats to me, but I kinda hope not, as that would be the 3rd time they'd be reprinted in 5e!
Looking through my old Monsters of Faerûn book, and I noticed that the monster in the first picture (from the D&D Beyond page for Adventures in Faerûn) is totally an ice serpent!!
After seeing this image, I now want a wemic PC species, solely so I can play Dirk Thunderkick, a spellcaster who speaks exclusively in dated slang, and talks way too loud.
"RADICAL!"
The 2e and 3.5e spirit dragons didn't have breath weapons, but had a "waterfire" ability to create fire underwater. I don't doubt that they'll have a breath weapon though in 5e!