I know Bioware had a really hard time with the ''suicide mission'' from Mass Effect 2, but it was so freaking AMAZING. knowing you could lost everything if you take the wrong decision or if you didn't upgrade your ship enough. They had the opportunity to do it here (again), with your castle and army, you could have had a ''huge final Battle'' against Corypheus and his army full of demon, darkspawn, red Templar etc...
First, corypheus could have came out of nowhere with his army from a portal or something to attack your castle and depending on the upgrade you did on your castle you could lost a huge part of your ''army power'' because they were able to break in too easily or you didn't had a watchtower to see them coming before it was too late to prepare yourself.
and then, you could assign some of your military force that you've recruit like the Mages or the Templar to defend certain area of the castle while you get to corypheus, depending on who you chose or where you put them you could actually lose the battle and have a bad/dark ending.
But maybe in the next Dragon age...
I've had these thoughts, myself.
In fact, whilst playing that "final battle", I wondered, is there a chance one of my squad mates/companions could possibly die?
Cause I tell you.. I'd actually be mildly bummed if some of them did. Well... namely Sera, who was my Inky's love. And Dorian, cause he was my mate. Oh and Cass... lot of respect for that woman. Others though... not so much. Joy there. 
But yeah... I was thinking this due to having to upgrade Skyhold, thinking it might follow a similar approach to ME2.
I think this is what is missing from the story and the climax -- a sense of importance or urgency. Where what you actually did during the game made a drastic difference. I recall my first ever ME2 playthrough, and being complacent when it came to winning some companion's loyalty. I paid for it and was genuinely in shock when I finished the game. Even if I didn't really care for them I was thinking, "**** I didn't want you to die!!"
Plus... a much more "epic" battle would have helped, with a chaos that rivals that of DA:2 and even ME2. Hell, Origins was chaotic and had one of the best endings going. I like to get my blood pumping, and bashing Corypheus in the head a few times doesn't really cut it.
Disclaimer: Just my opinion.