Whilst it's inevitable, given the current situation, that whatever power up Sakura gets will pretty much bring her up near Kage level...anything big will feel like too much of an asspull, let alone a full on Sage mode.
There's has been little to no build up of Sakura gaining such major abilities; it's so sudden that it just seems like Kishi's is pulling things out of his ass as he goes. Then again, it's felt that way ever since the war started, so who am I to complain...