Things are getting bigger...and smaller...
From a revenue (and margin) perspective, SAN and NAS are shrinking. But there's no reason to believe that their capacity-share in the datacenter is going away. I just talked to a large retailer who has >5 years of POS data (>10PB) still stored in their Vmax and no plans to archive it soon. In other words don't underestimate the stickiness of traditional workloads with traditional infrastructure. It is clear that the storage world is bifurcating towards AFA+NVMe for IOPS, and towards Object Storage for persistence and protection. But that transition is slow and objective.
Here is what matters: When large OEM storage margins shrink steadily over time, R&D budgets shrink with them, and high-margin products (*existing* products to be specific) get resource priority. This vicious cycle means that customers MUST NOT look to large-OEMs to aggressively reap the benefits of ASP reduction, and they MUST NOT look to large-OEMs for R&D innovation. Listen to your analysts and make sure you are allocating time to hear from up-coming vendors.