Except that "opportunity cost" doesn't require cash. Refurbishing a plane does. I don't know how they treat those programs from an accounting perspective, but I assume those cabins are depreciated over time, so the net income impact can be "buffered" (calling Professor brunos for help). But Air France still needs to pay the invoice of the company doing the refurbishment. Even if things turn out very well and airline travel rebounds then all the revenue generated then will be needed to pay off huge debt (looks like the French and Dutch governments will guarantee some massive loans), and reduce the FY loss. And on the cash side, it will be kept to (re-)create a buffer after current cash reserves are depleted in the months of March-May.

So the best thing we can hope for is that AF sends the non-refurbished planes to the desert (A380, A340, the NEV4-777s) and only keeps the refurbished ones flying. That way the likelihood of being on a plane with a refurbished cabin will increase dramatically.