IPv6 Adoption over the years?

JR0c

This discussion post that I encountered from my school was asking about why is the worldwide implementation of IPv6 slow? After researching on this, many articulate that it is quite expensive and also has compatibility issues, at layer 3 IPv4 which is a 32 bit and comes with common classes A, B, C, and D producing up to 4 billion addys. For IPv6 it is a 128 bit address, assuming the production rate number is tremendous. Could some one just pick my brain or see if this is accurate and enhance my knowledge on IPv6. Any thoughts and feedback would be helpful from anyone.
lol ig ppl are to smart here to reply.