Lizzies would probably start using steam/etc. technology(since their technology is... primitive compared to armies such as Empire and Dwarves), as their technology is very very slow in progressing(they're so old, come on. They're immortal pretty much[AFAIK
, they can't die of age]). Beastmen would probably be similar.
Empire would most likely be the most technologically advanced, and possibly Skaven as well. Using modernish/futuristicish(such an AWESOME word!) technology.
Skaven would likely be mutated beyond recognition of rats, as I imagine radiation and mutations would carry on through the generations and getting even worse.
Vampire Counts and Tomb Kings(to a lesser degree) would likely follow along with the technology of other armies, having a mix of what they have, with Tomb Kings being slightly less advanced than Vampire Counts.
That's all I can think of.