There is still quite a long time left and a lot of matches. Performing at a steady full strength avoiding defeat is Arsenal's best way to stay afloat of Man City's pursuit. As long as this season goes on I think only these two Teams have a chance to win the EPL this season.
Newcastle, Tottenham are still too weak to compete. If Newcastle and Tottenham don't make any major changes to the transfer next winter. A slight mistake from Man City or Arsenal will make a big difference. Right now I feel like these two teams are still the same.
Avoiding defeat (or even draw for that matter) would of course be the key but is it as easy as it sounds? I mean yeah they have played very well so far but that doesn't mean that they can keep doing it forever, and eventually they may end up with some losses and it could cause some trouble for them.
This is why I believe that they could end up with a lot of trouble if this keeps up, and they could end up losing points on weeks that City gets a win. That consistency of winning is not a simple thing, specially not simple in Premier league, which is why I see the chances of Arsenal lower than City even while they are leading the league. Maybe I underestimate Arsenal, but that's how I see them.