Nolito has been producing good numbers for years and I'm sure he'll be somewhat useful. But he's soon to be 30 and that's no long term investment.
Gündogan is a truly great player and worth gambling on despite the injuries. But that still leaves them in a position of having to sign at least one midfielder to start now when he's not available. And even then, I'd say that they should maybe sign two, as they still could use a new holding midfielder.
Two ball playing central defenders, two fullbacks, two central midfielder and a good dribbler who can play out wide, is what I think they should sign. Their transfer policy in recent years, has been questionable to say the least.
Still think they will win the league though. I'm sure Guardiola will do some interesting things, even if City's current squad is not what he's used to working with.