This question never needs to be asked ever again because for every single season we have ahead of us we should be looking to challenge for the title, get as far as we can in the Chmapions Lg (the difference between getting knocked out in the quarters and winning it was about £8m for Chelsea, that's all!) and if we win a domestic cup comp then that's a bonus. That's it. Forever more.
We wont win the league every season. Some seasons we'll finish third. Some we'll challenge and just miss out. Some we'll win. United will continue to win titles, don't ever be so naive to think their success is over. There may be times we go two or three years without a trophy but there will be years where we win two or even three trophies in a season and we might be so good one year where we win the lot. We shouldn't ever flap if we have an off season (it will 100% happen, guaranteed!). We should stick with Mancini and dust ourselves down and go again the season after.
The only time we should be concerned is if we ever look like we wont finish in the top three or we go more than three years without a trophy.
That's it. Enjoy it. Being a City fan has always been great (even at our deepest depths I loved it) but now it's dream land.