It'll need to be still flying (if that's the correct verb) in order to recoup the costs.
2nd thought: The costs, of course, will continue on the exponential curve.
"... retrofits that would allow airlines to add up to 70 seats."
May we assume that to mean the removal of first-class suites?
Mark (et al); you're beginning to show your petticoat.
How many versions of the F-35 will there be, eventually?
You've hit it on the head Tommy. L.M. (Like Money) will not accept the T.T. (Trump Test). The U.S. aircraft industry moves into a new era as it realizes the need to do business with (at least)...
Hybrid power for takeoff and climb; Conventional power in recharge-cruise; ePower for descent. Technology is available today.
As Nike tells us; Just Do It.