I think if we could fast forward about 20 years, you will see only electronic shifting on new bicycles, even cheap ones, it's simply easier to build, because the wires don't need to be at specific tension and don't need specific routing. Having said this though, considering that there are a lot of 30 and 40 year old bicycles around, I don't think that cable shifted bicycles are going to disappear anytime soon.

What will be interesting though, will the manufacturers do what the electronics industry does, generation 2, has a different battery design, then generation 1, so that the manufacturer can stop making generation 1 replacement batteries forcing you to replace the entire system when the battery fails to charge. These batteries are the same voltage, same amp/hrs, but the battery is a slightly different shape so that they don't fit in the same physical space.