If the block size gets increased twice as much, the miners' profits obtained via transaction fees will most likely decline since there will be no more competition between senders for faster inclusion which leads to rising fees. So we shouldn't expect miners to accept SegWit or other measures to increase the block size any time soon
It's going to be really intriguing to see who blinks first. I'd guess that many of the current users are using it as a curio and luxury rather than having any pressing need. If the price keeps on rising then I suppose enough people will swallow it for now but I wouldn't underestimate the willingness of people to walk away.
Anyone using it for commerce from either direction must be not too far off shopping elsewhere, or they'll all go off chain such as the merchants now only accepting sales from Coinbase wallets.