Given how old lore and spirits tend to act, it is entirely possible the dread wolf is referring to real monstrous figure. But I think the elvhen figure is fighting this creature rather than beckoning it. I mostly say this to counter the interpretation that the elf is 'inviting' either the shadow wolf or the red lyrium idol. To me, that arm position looks less like an invitation and more like he is warding off or deterring something. Which sort of makes sense since Solas is more than averagely cautious of anything pertaining to the blight/red lyrium ("Those who believe themselves capable of using it [blight] safely are mad").

But assuming the Solas vs. Dread Wolf fight is entirely metaphoric (as in, not representing an actual spirit/figure):
It could mean Solas is battling against what he 'should' be (the Fen'Harel who made terrible but necessary choices), the 'monster' modern peoples tend to paint him as (The Dread Wolf hailed a malicious trickster in Dalish legend) or...he is simply an elf by the name of Solas, who has to deal with the mantle bestowed on him by his followers due to forces either outside of his control or potential calamities that only he decided to deal with (represented by all the stuff in the middle of the image). It would be Solas's version of Leliana's softening/hardening.

If true, it could point to Solas going through a spiritual change in the next game. Which isn't too different from what we have in DAI to be honest....if Trespasser and the main game was any indication, Solas can either have his initial disdain/despair of the world reinforced (negative approval) or eventually see value in the world (high approval/romanced). And seeing as how DAI original story line was massively reduced, it makes sense that Solas's personal character progression was left as inconclusive as his story.