True, 2X is insufficient. As is 8X. But they are steps in the right direction. The only direction that will get us to our goal. Larger blocks are a requirement for Bitcoin to be meaningful to humanity as a whole.
"The payment network Visa achieved 47,000
peak transactions per second (tps) on its network during the 2013 holidays, and currently averages hundreds of millions per day. Currently, Bitcoin supports less than 7 transactions per second with a 1 megabyte block limit. If we use an average of 300 bytes per bitcoin transaction and assumed unlimited block sizes, an equivalent capacity to
peak Visa transaction volume of 47,000/tps would be nearly 8 gigabytes per Bitcoin block, every ten minutes on
average. Continuously, that would be over 400 terabytes of data per year."
Over the long term, not a problem. How big was your disk a decade ago?
Note also that this is peak. We can tolerate transaction backlog, as long as it clears without too much time passing. Average is much lower. Note that the published paper makes a
fundamental logic error. Using a peak figure as an input to an average calculation is either gross stupidity or simple fearmongering.
Now lets actually discuss how we get Bitcoin into the hands of each and every person. What's your solution for that? Hmm?
What I'm trying to say is that we can't solve the throughput problem
in the long term by simply increasing block size. It will let us breathe for a while and then choke us again. Other, smarter methods should be employed for solving this problem. One proposal is the Lightning Network. There will be better ones to come, and we should embrace them.
Regarding your 30-year calculation, it is indeed correct, and is an interesting result. SegWit gets this reduced to 15 years. This duration will be decreased further by increasing the block size. But it still won't solve the throughput problem. Perhaps a combination of gradual block size increases, as permitted by h/w capabilities,
and good off-chain solutions are actually needed.