They could be doing this a bit for the optics, undoubtedly also for the bottom line. A lot of cost is sunk cost, unrecoverable, but also you have to believe the backlog of orders could be swung behind a new jet which carried less taint of the certification stuffups, and carried with it some of the more recent cost improvements for an airline's TCO.
I'd consider this a hopeful, win-win situation. On the Boeing balance sheet, the max won't be regarded as a fruitful place to have landed: better to take off and go somewhere else.
If Boeing management were focused any further ahead then next quarter, they would’ve drawn a line under the 737 with the NG and started work on a new type in the early 2000s, and avoided the easily forseeable situation they find themselves in now being outgunned by the A320 family.
I'd consider this a hopeful, win-win situation. On the Boeing balance sheet, the max won't be regarded as a fruitful place to have landed: better to take off and go somewhere else.