Yes. The 1800X enjoys a comfortable lead over the i7-7700K in non-gaming workloads, but not a huge one. Intel is about to introduce 6-core processors with Coffee Lake and I would expect those to close that gap, and perhaps even overcome Ryzen. There will probably be Skylake-E SKUs with 8, 10, and perhaps 12 cores as well.
So I think AMD needs 12 cores to maintain Ryzen's edge, which shouldn't be difficult on a 14nm process that is already pretty mature now, let alone next year, especially when Ryzen is apparently something like 215mm². The other option would be for Pinnacle Ridge to have at least 10% higher IPC compared to Summit Ridge, slightly higher clock speeds, and fewer issues with its interconnect and memory subsystems. This is possible, but adding more cores would be easier, and not incompatible with any of this.
Alternatively, AMD could make relatively affordable—$1000?—versions of Naples with 16 cores, essentially offering something comparable to Intel's HEDT platform, but with much more raw power.
On a somewhat unrelated note, the R7 1700 seems to be really, really power efficient:
http://www.hardware.fr/articles/939-2/consommation-efficacite-energetique.html
I think the last time AMD was clearly more power-efficient than Intel at anything might have been in 2006…