If the MAX is permanently grounded Boeing could revert back to producing the B737-800 series and selling them at a deep discount, possibly just over the cost of production, while they work flat out on a new narrowbody replacement to compete with Airbus. This would keep the factory going, the employees paid and the customers reasonably happy. Any airline agreeing to take a 800 instead of a previously ordered MAX could receive guarantees regarding price and delivery date when the replacement becomes available.
Taking a less efficient aircraft at a very low price and operating it for a few years, then replacing it with a brand new design which would likely offer a slight improvement over the A320 NEO could work out for some airlines.