Mage Companions Available for DLC [SPOILERS]

Hello all!

I'm currently doing my second playthrough of Inquisition. During my first playthrough, I did the Jaws of Hakkon and Descent DLCs before fighting Corypheus, but because my character was so high level at that point the "final boss" fight was comically easy. To hopefully get a better experience this time, I decided to leave the DLCs until after the Corypheus battle. I knew that Solas would leave after the battle and therefore wouldn't be available during the DLCs, but what I wasn't counting on was Vivienne being elected Divine (I supported Leliana, but I know that doesn't guarantee a particular result) and her also being unavailable as a companion. Thankfully, Dorian decided to stick around, so I'm not completely mageless, but isn't it also possible for him to return to Tevinter? That's what he said he was going to do in my first playthrough, but since I jumped straight from the Corypheus battle into Tresspasser I'm not sure if he actually left or not.

Basically my question is, is it possible for all three mage companions to be unavailable after the Corypheus battle? If so, does it make more sense to play the DLCs first, especially if you're not playing a mage Inquisitor? My first playthrough was with a mage, so it wouldn't have been as much of an issue then, but I'm playing a rogue this time and I admit to feeling a little panicked when I saw the party selection screen.

Thank you!