There's absolutely no chance they will win the league within the next 5 years. They'd have to go from relegation candidates and overtake City, Chelsea, United, Liverpool - even established teams like Leicester and Everton struggle to do that. I don't think some of these people realise just how good we are either! Even if we had a poor season, we'd finish 4th and Chelsea would win it. Even Liverpool nearly matched our 100 points season, that's how high the bar is.
When Mancini won it for us, I don't think - at the time - we necessarily realised just how good some of our players were. Kompany became a legend that season, Silva was outstanding, Yaya changed games on his own, Hart was world class, Aguero was world class, Zaba was outstanding, Tevez was world class, Barry was very solid, De Jong was outstanding, Clichy was solid. That's nearly the full team who weren't "megastars" when we bought them, but became legends with the right manager. You just can't buy that! Plus, how long did it take for us to replace Kompany? Who'd have guessed his replacement was hiding in an average Portuguese league!
If they want to win the league "quickly" (6-7 years) they'd have to probably have the best recruitment drive of all time. It will cost a LOT - probably nearer to £2bn than £1bn as well. Unless they are going to break world records, I just don't see them winning the league for at least 10 years, no matter how much money they have!