Not sure if this also applies to Serie A, but in some leagues, the winner is decided based on their second-half performance of the season. I remember that Man City usually stumbles in their first few games over the last few years (including when they won so many trophies). I think the competition was even tighter last season, right up until the last few games for Serie A, too? So yeah, I'd also think twice before making a bold prediction on who will win the league this early in the season.
Yes, it's something that can't be predicted. There are teams that have won by a significant margin, like Inter who won 5-0 against Torino, but it's very difficult to understand who could win the championship. There are certainly teams that are already imposing themselves, but it's really difficult to understand on the first day. I wouldn't make any predictions.
Inter Milan has taught me a lot of lessons last season which is why I was not moved by their Victory. It will be to early to point at any team at this point, this was just their first game of the season which was quite right, they very well which I cannot deny them the credit because despite they where playing against the weak team I was impressed. I was not surprised even before the game because I knew how aggressive inter normally play anytime they faced weak teams. I will applause them if they can play like this when facing tough teams like Napoli and others.