CTO of Modern Treasury here. Banks are actually starting to setup a new payment system between themselves called Real-Time Payments (RTP) which has a lot of the same benefits as wire transfers. RTP is 24/7, instant, and (from our experience) much cheaper than wire transfers. It's starting to roll-out across more banks and currently ~50% of bank accounts can receive RTP transfers [1]. I just cashed out on Venmo the other day and their instant transfers are going over the RTP system. Other than coverage not being complete, one of the main downsides is the $25,000 cap which means that for higher dollar volumes people will likely choose a wire. If you're sending $1mil, then the $35 wire fee doesn't seem like so much in comparison.
[1] https://www.theclearinghouse.org/payment-systems/rtp/institu...