I don't think Arsenal are in any crisis and my head tells me they'll finish top 4. They just finished level on points with Liverpool despite spending most of the season without Henry and Van Persie. Henry has been replaced and Van Persie is back and fresh. Their youth is that bid older and more experienced now, and I expect one or two to step up the way Eboue, Toure etc did before them. Diaby, Adebayor and Walcott should all improve and Van Persie was on fire before he got injured last season.
However, Gallas's quotes do suggest all is not rosy there and we've seen ourselves how a few bad eggs or poor morale in general in the dressing room can really disrupt a team's unity on the field. Heads go down a lot quicker and a glass half full becomes a glass half empty. They need a good start to the season to avoid that, they really do.
We only play the 'big four' a total of 8 times in the league. The rest of the season consists of 30 games. People often look at it negatively, assuming we have to be a better team than Arsenal to finish above them. In fact, we just need to be more consistent, picking up as many points as possible in those 30 games and trying to get whatever we can against those teams bigger than us. When Everton finished 4th and Liverpool 5th, Liverpool were clearly the better side, but failed to produce the points quite as consistently. When we finished 3rd under Bobby Robson 4 years ago, we were considered outside title contenders by the media until the last few weeks of the season. Clearly Man Utd and Arsenal were much better teams than us, but we just kept picking up the 'easier' points and focused only on ourselves. It's not about comparing us with Arsenal, it's about picking up more points than them against teams like Reading, Wigan, Derby, Boro, Villa etc, etc, etc.
A couple of good defenders and a real injection of quality like Deco, coupled with a bigger squad and a better manager, and maybe we'll be picking up the 'easier' points more consistently. As for Spurs, I don't think we're behind them at all, for a large part of last season they were distinctly average before making a charge, just as we did the season before finishing 7th. Also both Spurs and Arsenal have Europe to worry about, we don't, and that could make a significant difference when the fixtures are coming thick and fast and they're flying to Tblisi or wherever while we enjoy a midweek break.
I'm more worried about us, if we sort ourselves out we can pick up points regularly and let Spurs, Arsenal etc worry about themselves.