We obviously need a bigger block size if we want to challenge the big payment electronic systems. My main concern is that the people running nodes could be severely decreased due the blockchain being bigger than ever.
If we wanted to challenge the big payment electronic systems it would not be decentralised because the multi-node redundancy scales like O(N), N- number of node sites, i.e. it gets expensive rapidly.
Compare with SWIFT or Fedwire for something relevant, at this stage of technological development (one day it may be possible that all google's data is stuffed into the blockchain, not today).