"Im sure that in 20 years there will either be very large transaction volume or no volume."
This sentiment unsettles me. This all or nothing attitude is defeatist.
Or just that he understands the economics involved.
Please tell me what do you think will happen IF If in 8 years we have negative growth but a 2mb or even 8mb blocksize?
Will transaction fees alone be enough to secure the network?
Will miners process torrents of spam for dust?
Will our network be stronger or weaker?
Are you willing to risk everything on the unfounded assumption will continue to grow, grow at a never before seen rate and for years?
What do you think happens if your wrong?
Bitcoin will be dead. Regardless of block size.