City to me is the only team that can usurp them, but it's going to take some doing, city needs Liverpool to drop points, while also avoiding dropping points, it's a difficult position to be in, the season is still hard and long, it's still open for most of the big six, but klopps men are favorites as it stands.
I think physical fitness is probably the reason one of those two teams will drop points. Liverpool has busy fixtures. On top of that, their back-up is perhaps not as good as City. However, they have some fantastic talents with Brewster on forwards. We'll probably see them play with 4-3-2-1 more often and try to use their midfield who probably have a lot of stamina to keep pressing the opponents. Liverpool 2nd half against Chelsea shows that they might be tired too. But who knows, Klopp is a good coach, and he can push his players to give 120% if it's needed.
Again its still early to say anything and probably it will take some time to say more but this first several games suggest that we will see City and Liverpool battle for title and it could be great to see champ is decide in last few games.
I don't expect them to finish with less than 90 points if their form continues like this. One of them probably has 100 points or so, and the other will be around 97 points or so. The only significant difference between these two teams is that if City is going to win, they'll win it big, but if they got one or two-goal conceded, they could drop points. On the other hand, Liverpool is not 'that good' with dominating their opponents, but they always work hard and make a comeback. They only failed to do it against City last year.
Forget Barca and Real. City & Liverpool rivalry is probably going to continue for five years or so.