What's valuable isn't the transistor and the internal combustion engine themselves per say, but rather the new networks they enable: rail, roads, informations, etc.

Blockchain is also a new network, and the math for analyzing its value is the same as the math for analyzing the value of any other network. In this case I would say that it's going to be the most valuable new network since the rise of global shipping during the age of sail.

Actually the blockchain might be #4, behind the discovery of the concept of atoms and molecules and the resultant birth of modern chemistry in the 1600's.

Those had immediate applications which made new capabilities possible. Blockchains are neat tech but nowhere near that level of impact yet.