Most pretenders to top 7 have European commitments apart from Roma and Inter, and Napoli have CL which is more consuming. Fiorentina are solid in defense, have a good midfield that retains possession and which is difficult for most teams to play against, decent wing backs (one of them, really good) and they also have plenty of options forward. They have a quite a few new players so it's not certain they'll do well right away and there's always the chance they collapse (doubt it), but if they gel they'll be competing for second, no doubt. Solid foundations.
I don't think Milan and Inter stands a chance against them, Napoli maybe. But then you also never know with the Milanese team I could be wrong, we never see them high up but they surprise sometimes, especially Milan.