You really think they're going to make a PC god tier?
I didn't necessarily mean as an actual companion but the point still stands. A god that's both willing and able to fix things is problematic for storytelling because you need to come up with reasons why he doesn't just fix things. Why is the protagonist even necessary?
When everyone has magic and we're not playing the Inquisitor any longer, it probably won't seem that overpowered. Because everyone is going to have magic... and she's got the Anchor, which is already super-powerful.
A PC can be god-tier, if we aren't playing him/her anymore. But equally likely, Lavellan/the Inquisitor is going to have to die.
I can't see them setting up Fen'harel for three games, only to let him fall as soon as he appears, via a DLC or something. No, they want him around for another game or two to influence things. Probably, next game, he will be either a catalyst or an accidental villain. We may end up needing to kill him at the end of the game, or a more direct villain may appear as a result of his actions (everyone having magic, the Veil being dropped... yeah, I can't imagine anyone taking advantage of that, can you?--I am being sarcastic here.), Either way, once we are no longer playing the Inquisitor, there's nothing but plot to keep Solas and Lavellan apart.