Math can't be your strong point.
They could have sold them for a combined fee of ~£100m in the summer. City were bidding over £50m for Sanchez alone. Real Madrid made €58m (or around ~£50m) for winning the CL last year and they were by far the highest earner. Arsenal have been averaging ~€30m earnings form CL participation, usually going out in the last 16 phase. They could still get £30m for each if they sold them in January, and get more than double the money that they'd lose by not being in the CL next year.
Not to mention the replacement cost. How much would it cost in the current market to get the next Ozil or Sanchez at prime age? They cost a combined £70m when they were bought, now it'd be what? Double that? Most likely. Are Arsenal going to sink ~150m in the market to replace them? 0 Chance.
This is all some posturing from Arsenal to show that they won't cave in to players. In the meantime they're cutting off their nose to spite their face. When Wenger eventually gets moved on, the new manager will have a mammoth task in making the Gunners competitive again with the terrible management from Wenger in the last few years. He has filled the squad with average or highly injury prone players that never get moved on, while losing his best players on a free.