Well, he was already playing on the top line and had the coach's confidence, so it's not really going to improve his situation.
But, as Vegeta has hinted he plays a smart defensively-responsible game and in that sense has been a good complement to Pacioretty (who can be lazy on the back check) and Radulov (who can seem lost in his own zone). I think he's the type of player Julien will appreciate, so this isn't necessarily bad news for him.
That said, Therrien had a very short leash on Galchenyuk (rightly so in my opinion). Julien might have different ideas on that front, at least initially. That might take some opportunities away from Danault.
Danault is clearly a solid two-way NHLer, I think the jury is still out on whether he belongs on a top 6 full time.