I think the problem for Spurs is that there are two teams averaging 2.5 points per game. As well as you are doing, you still need both to drop off the pace to some extent. If either maintains this form, Spurs have a near impossible task, Smart.
Jan and Feb will be crucial for Spurs and Utd with some tough away games. City have the easier fixtures on paper with home advantage against Utd, Spurs, Chelsea and Liverpool in games to come- hence most pundits (and the bookies) favouring them.
I'm not doubting Spurs ability to challenge, but it remains to be seen if this form can be sustained all season. Even a big improvement on recent seasons to 75 or 80 points won't be enough. I doubt 85 will be. 90 may be, but at almost half way, the trend would suggest 95. The top sides may take points off each other- Spurs will need to- but none of the top 3 has looked like dropping many points to any teams outside the top six.
So I stick by what I've said