First part, Arsenal would make more profit being out of champs league and spending 60mil less on wages. Arsenal profits are not huge, neither have the owners extracted loads of money out of the club. The fact that the 154mil is in Arsenal's bank account to protect the club is proof of this. That would be safely in the owners accounts being used to fund some new business elsewhere to make even more money if that was the case.
The second part, the fundamental flaw with Wenger is he actually genuinely believes Diaby is one of the best midfielders in the world, he thinks Diaby is brilliant and though Song was brilliant, he thinks Walcott is brilliant.
Replacing Ronaldo is basically impossible, the problem with Wenger is, he thinks he has a team full of Ronaldo's.
Again what reason does the board have(in terms of milking profit) for repeatedly giving Diaby new contracts? None, at all, Wenger however thinks he has a potential Fabregas on his hands if he can get Diaby fit and has therefore done his best to keep him and doesn't want to replace him.
He saw something in Gervinho that said "world class striker", and let Vela walk away for next to nothing. Everything points to Wenger being the problem, nothing at all points to the board being a problem. If the board were the issue, Diaby would have been shown the door at the end of his first contract, Walcott would have got told to do a running jump when he asked for 100k a week, Santos would never have been bought, and there wouldn't be 154mil in Arsenal's bank account.
One question I've always had, does Wenger get a bonus based on financial performance at Arsenal, does offering 3mil less for a player end up in him getting say a 300k bonus come the end of the year... lots of other managers have such deals in place, for me it would also explain a lot.
One thing to remember though, it is the same board who want to offer Wenger a new deal!