Actually yes
1. Drones are just miniaturised versions of WWII tech/transistors
2. Electric cars, first ones were around 1884
3. Mobile phones....extension and smaller version of the car mobile phone which originated with the
Bell System, and was first used in
St. Louis on June 17, 1946.
So yep all old tech made usable by smaller batteries, which as you rightly point out are currently fufilled by lithium ion batteries. However they all started out with lead acid or similar batteries and as battery tech got better and smaller they got better and smaller.
However the lithium ion battery was only commercially made from the 1980's and the hunt still goes on for lighter, smaller, more powerful batteries, (and of course cheaper). Battery tech is not so much about cost as about convieience, as such Lithium ion will disappear the same way as Zinc Carbon.
But I looked at and agree that lithium miners are attractive if you can get into one at the start that has their mine in a stable country. If you have done that good luck with your investment.
As for A2, you are right, the product, as is lithium is not patented to A2, (although the herd testing process is), however A2 is a brand that is seeking to be the recognisable brand when it comes to A2 milk, so that consumers will think of the brand as one and the same with the product, that is where the power of A2 is.
p.s. check out the Aluminium Air battery, at the same point now that Lithium was in the 80's/90's
(20min delay)