Do Oracle's existing customers still have Oracle on their longer term road map?
If the answer is yes, then why?
Most likely yes.
It wouldn't surprise me of many SPARC/Solaris shops wouldn't have virtualised on LDOMs and containers. The T4 and T5 series have pretty nice support for virtualising Solaris environments in a resilient way.
It is easy to forget that many large corporations (telcos especially come to mind) have long history on Sun hardware and may have bespoke software written specifically for the platform with proven and predictable performance.
Of course it no doubt could be migrated, but why risk it. As I mentioned virtualisation options on later T-series enables sweating the assets lot better than some of the older hardware so migrating onto x86 for example may not yield such great savings.