I can definitely see an update for basic Eshin ninja rats coming via a warcry squad, seems like the perfect venue for that sort of light skirmish unit, really. And personally I don't think you necessarily need all the clans to be equally represented, the sneaky assassin clan with a hero, monster, and skirmish unit feels reasonable for that sort of theme. I guess maybe you could re-flavour jezzails into a skyre/eshin cross-clan sniper thing, or something.
Plague Monks, on the other hand, don't feel like a good fit for warcry. Warcry squads tend to be 8-12 ish models and they have to fit entirely on two standard sized sprues, whereas plague monks have historically been more of a horde unit (though I guess, again, they could just reflavour them into something more elite.) More likely they'll look at things like pestilens as part of new release waves in later editions, prime candidates for a supplement as part of a future broken realms/dawnbringers style series, for example.