What about hybridization, for starters?
OK, so conditions in the existing coffee-growing regions change enough to render the current varieties of Arabica untenable. There are several possible responses to this. For instance, begin research to develop varieties of the bean that are more tolerant of the new conditions of these regions. Begin planting Arabica plants at higher latitudes, where presumably the warming happening at the lower latitudes would be less severe. Research modification of the Robusta plants to improve their taste, yield, caffeine content, etc.
Hand-wringing at this stage is hardly the response I would expect from die-hard coffee drinkers.
