A five points gap is great for Arsenal, not so comfortable, but in the EPL i don't think any team would expect to top City by a comfortable mile, if they (City) are not top, they'd always chase whoever is top and maintain a considerable distance so they would be able to capitalize on any errors, thus Arsenal should be happy with the five points gap they have at the summit.

Having said that, Arteta basically just has to get on with things immediately after the WC, if they lose concentration, City are going to be there to take advantage, for now City are yet to have any player injured at the WC, but Arsenal do, Arteta has to start working on how to cope without the players he is sure wouldn't be available immediately after the WC. The thing about Pep is that he never stops thinking, so if his team is breathing down your neck, you also shouldn't stop thinking, or else he'll win in the end.