I have read the article, unfortunatelly I do not agree to their theory.
400 million people using bitcoin in the year 2030 seems very unlikely to me.
I an sure bitcoin will grow, but not in such a magintude.
They don't have to actually be using Bitcoin. They can be using any service for which BTC is the reserve currency that the whales of that services settle their commerce in BTC.
This is why scaling doesn't need to be on Bitcoin in order for Bitcoin to benefit.
The maximum transaction rate is still too low for an effective commercial settlement system. It can't handle SWIFT traffic levels for example, and that is just for settlement between financial institutions. Then its status as a reserve cryptocurrency becomes under threat.
SWIFT is not restricted to power brokers. SWIFT allows any Joe Blow to wire $1000.
Bitcoin's block size is more than sufficient.
The entire point is to keep the riff-raff off of Bitcoin, so it doesn't need to be regulated. And isn't constantly assailed with such nonsense as UASF.