Chasing Manchester United premier league win will be very difficult or impossible to achieve, atleast in this our time. 6 English Premier League trophies means 6 seasons and looking at it, the highest Manchester City can go before being dethroned as the indisputable champions of England is 1 or 2 seasons. If you look very well, Newcastle is just building and Manchester United is gradually coming back to form and Liverpool is there to always contest. There will be a time the reign of Manchester City will also come to an end.
I think it is not that much difficult given how Guardiola has managed City ever since he took over as manager. He has made then PL champions 5 times out of 7 seasons and that really shows the kind of spectacular record Guardiola hold rights now. I think in 8-9 seasons he can make them equal to United if things goes like this. City are in control in whichever way you see and despite United and Newcastle improving, I don't see them getting dominant the way City are right now. I would say its very much achievable if Guardiola says for long term.