I think eventually we'll have a game dedicated to some crisis or some situation the elven gods have concocted - I mean, arguably Inquisition is inadvertently that, but I hope for a world-changing event which was deliberately caused, where the gods step out of the shadows.
DA:I wasn't really the right game to introduce the entire pantheon. The game began as something very chantry-centric, and depicted faith in a traditional way (for most western audiences, at least), and prior to the Temple of Mythal at the very end, it's thought most elven gods are little more than myths and legends. It seems the dragon age team want to show us that the reality of the pantheon is much more complex than what exists in legend - I think a lot of this includes fleshing out characters, which we've seen with Flemeth and Solas, showing the complexity that arises from being in an unique position, rather that introducing them as cookie-cutter arrogant, vengeful, power-hungry god villains. Which means they can't squish it in at the end of Inquisition.
DA:O and DA2 would have been the wrong places for such a plot revelation. DA:O was primarily focussed on introducing the darkspawn and the blight, and DA2 has a human protagonist looking at contemporary struggles between templars/mages, where "ancient magic" didn't play a big role (that plot was introduced in DA:O too - see the plot arc in the circle tower, or half your conversations with Alistair and Morrigan).
I don't see why 'three games' is the absolute maximum a plot can be dealt with. Really, the pantheon plot has only been on the sidelines until now. They were possibly dragging out hints about Flemeth, sure, in DA:O/DA2, but as a fully fleshed idea it's only began to take root in DA:I.
Plus, it's too large a plot element to make anything other than an entire game dedicated to it, and it's introduced too late to make DA:I about it.
It's late and I was scrolling through my Tumblr feed (which of course is flooded with DLC stuff), and uh... that over the shoulder still of Solas kept popping up. I couldn't help myself.
I actually would fancy him a thousand times more if this was true.