With the previous economic crisis ( if that one had passed by is a different question for other forabut it's not like the economy is going to improve in the next years, in fact we may not have reached the bottom yet.

Less flights, no more business class. Some did even turn to LCC's ( while others maintained their veto against LCC's, but that is also another subject )
Reducing costs is an obvious way to go and the theoretical graphic shows that every company should stop all activities immediately. ( which is of course irrelevant )
So we follow your theory again of reducing the size of the airplane . Theoreticaly it would mean lower operating costs ( I ridiculised you before by proposing to fly Cessna's Caravan but I won't do that again ) And we all know how eager you show us the figures of 1 particular airplane, which would improve the numbers of SN immediately. Leasing or buying costs money. Even for a Q400.
Btw, flying Q400 doesn't mean you can't go bankrupt...

But several members tried to convince you of the danger of reducing capacity. OK, crisis means less sold tickets. So a company has to fight to get those remaining customers. And 1 way to do this is by reducing the price and fill up the plane. Without giving up the premium paying customer. (who wants the connections of the group, the miles, service, international airports and yes, even still some of those who fly real business )
Increasing revenue is the other way : a higher price for the same product is not possible now. ( many companies' bookkeepers found out about the Flex tickets which carried about the same price as before, and the result was that many sales people were bluntly told to fly less

Other excercises such as expanding the network should always remain in the framework of cost reduction+ revenue increase. Code sharing sounds nice, but who wants to sell the product of another company if the revenue is for the partner airline?
There is no magic trick. Running a company demands daily attention, flexability, decision making.
I do hope for SN that their managment is allowed to work carte blanche ( oops, totally not done in Belgium with unions, politics, old boys network )
But I know that the current situation doesn't allow a company to be run differently as the competitors are being run: to make profit. That is and will always be the only reason of existance of a company.