We've already hit a perceived user experience limit. The perception of responsiveness in blind tests between SATA and NVMe SSDs isn't always apparent--people sometimes say the SATA drive is faster--even though the speed difference on paper is substantial.

IMO, programmers haven't exploited the possibilities of extremely fast mass storage yet. The orders of magnitude difference in speed isn't fully realized. It's not just faster, it's faster in a way that requires new approaches. Unlike multicore CPUs over a decade ago, this change in thinking has gone relatively unnoticed by programmers.