It's certainly interesting that people are exploring other options for creating hot dark beverages that taste at least somewhat similar to coffee, but it's also entirely possible that synthesized caffeine makes its way into other beverages entirely. Obviously there's tea as a substitute, but there are also lots of soft drinks and energy drinks with caffeine.

So long as caffeine remains cheap, increasing price of coffee will likely be met with caffeinated substitutes that have nothing to do with the coffee plant.