First off, I've never argues for them to be subsidized. I am just stating the perceived massive profits currently being made are dependent on subsidy. They would still make money in the NFL absent such subsidies... It would take a lot longer and it would be far more risky. A situation that isn't exactly ideal for attracting capital investment.
Red McCombs roughly doubled his money in real terms (adjusted for inflation). However, the Dome was paid for and the Vikings were receiving government subsidy throughout the period. The Vikings were receiving revenue from every event in the Dome in concessions, parking, and suite revenue.
They also didn't pay rent ($4 million) per year from 2002 to 2011; it was waived by the metropolitan sports commission.
Increases in value are dependent on cash flows. The Vikings and Mr McCombs's cash flows and subsequent return were dependent on subsidies at the time and subsidies projected into the future. I'm sure one of the country's billionaires will be happy to play the next fool. Btw, I have some "postal reply coupons" I'd like you to look at.
If you cut the players salary there is more margin assuming revenue would stay the same. Since football players won't become more productive, I highly doubt major cuts to costs would support the same revenue stream. I can't think of another business where that is true, or has been true in the past, absent some major productivity revolution.
However, maybe they could cut it to $200,000 a year and then they'll make millions....