I am not underestimating the surprises of teams, but one thing is certain which I believe Manchester City will beat Inter. There is different between having a smooth ride and struggle ride, Manchester City throughout their journey had everything easy, they at a point had Real Madrid on their neck but trash them in the second leg as if it wasn't semi final while Inter where struggling to defeat other teams, their match against Milan was luck and they made it out, now I think that luck ended in that stage. Manchester City will take their time to win this match which after they will go and lift the FA cup again.
Luck doesn't end when we think it will end. It ends when it actually ends
It wouldn't be the fest time that a team overcame difficult hurdles and struggles one after another only to then also win the final game.
If you want I can give you an intriguing example from the past. Do you remember who won the Champions League in 2010? You are right, Inter Milan. They had to beat not only Chelsea, but in the semi-finals also one of the strongest Barcelona teams we have ever seen managed by Pep Guariola. source
In the final Bayern Munich was waiting for them and Inter Milan showed a rock solid performance and scored two goals out of the very few chances they had.