Very true. It's hard to fathom the economy getting worse than it was for the last couple years...although we could conceivably get a double-whammy from the situation in Greece and a series of cross-defaults from a failure to raise our debt ceiling, so I guess it's possible that the league may have some macroeconomic concerns going forward. But the league is becoming increasingly global, and revenue streams from the rest of world (especially Asia) will only continue to grow.
And even if nearly every team were losing money, it's possible that the league as a whole is still profitable. With the luxury tax, many "losses" are a result of a financial shell game in which money is transferred from a team to the league and reported as a loss. Luxury tax expenditures may be substantial, but they are a product of poor management and entirely avoidable. Looking at some of the decisions teams have made on player salaries, it's almost as if owners wanted to drive down their revenues as much as possibe the last couple years in order to lock in a long-term discounted rate on the revenue sharing. After all, these owners generally didn't become billionaires by making stupid business decisions, and it may be shown to be a shrewd strategy when (not if) it eventually pays off.