Call me a mini-luddite.. I don't mind technology advances in the technology space, to a degree. I have a smartphone, for which I use maybe 3-4 apps on a daily basis. I really don't like that to keep my iMusic library, the lowest iPhone cost is now ridiculously high when I'm forced to 'upgrade' since my phone's processor will not be able to handle the latest OS to handle running the latest OpenTable app. In this vein, I wouldn't like a future scenario where bike shoppers don't have a choice to spend less for mechanical shifting.
Back to bikes.. Di2 is probably how I would go on a n+1, likely because it's closest copy to Campy ultrashift and more easily found -- especially in a disc-braked model. I get the 'purity' argument though. Look forward another decade, when there's potentially completely viable automatic transmissions, and motor assist (of course only when you really want it), and antilock braking, etc..
Is there any point (if it's not Di2 by itself), where you would come to think that the industry went "too far" -- and the "essence" of bicycling would be lost?