Not from Renard or from the expert he sent Juliette to see. The latter should most likely have known about the possibility, yet she unambiguously said that it was impossible for Juliette to ever change back.
Maybe Henrietta isn't as smart as she says? I feel like the writers should have at least had her mention the Grimm blood thing. I've seen the blood thing being brought up by countless fans on other forums, so I certainly hope the writers haven't forgotten that.
I have no faith in these writers' advance planning abilities. This show has been meandering with little direction or focus for the past two seasons.
I think I still like the first season's arc the best. Nick slowly discovering the Wesen world, the Wesen community reacting to the new Grimm, and Renard still being written as a potential bad guy. This was when Adalind still hadn't taken over the show, and there was just one episode about the Royals. It is very different from the following seasons.
Season 2 was all about the Juliette amnesia arc that went on too long. I STILL can't believe it took 20 episodes for Juliette to regain her memories, it had become a soap opera halfway thorough the season. Season 3 was all about Adalind's adventures in Europe and her magic baby which was just as dragged out, though I did enjoy Monroe and Rosalee's romantic development and Trubel's introduction during the final four episodes.
This season's structure feels much more scattered, 6 episodes of powerless Nick which should have focused way more on him trying to live a normal life, the Wesenrein arc that had a nice conclusion, and what looks like a big arc focusing on Juliette which I'm fearing they are starting to drag out with Nick knowing nothing.