Personally I see there being more market overlap between ARM and the P550 core however. Samsung, Qualcomm, Renesas are all planning to bring RISC-V cores to market. With performance between A75 and A76, I could see the P550 being a pretty major disruptor. We already know some RISC-V chips are gaining traction in embedded, IoT, RF, micro-controllers, etc. Automotive looks like the next big market for RISC-V to me.
Ampere is very competitive and Oracle have made huge investments into that platform, with Cloudflare etc looking at it very seriously as well.
Arm on servers is just getting started.
Just because ARM-M and ARM-A shares an instruction set doesn't mean that those chips are anything alike. Heck, ARM-M0+ is a completely different chip than ARM-M4.
ARM-R is roughly the target of RISC-V. (Realtime cores).
Previous SiFive cores compete against the A72 (announced but not yet shipping that I know of) and A55/A53 (shipping in the BeagleV "StarLight" beta and HiFive Unmatched and probably unannounced embedded applications).
In the four years since the A75 ARM has announced the A76, A77, A78, and A710 as annual incremental improvements (the most recent of which are not available in products yet), plus in a new higher-end line the Cortex-X1 and X2.
So ARM is not standing still, but SiFive is catching them at approximately two years of ARM progress every year i.e. closing the gap by one year per year.
https://www.arm.com/products/silicon-ip-cpu/cortex-r/cortex-...
I'd also expect features like per core TCM if this core was targeting ARM-R niches to at least break away from the non determinism of the memory hierarchy (particularly a multi core memory hierarchy!), but I don't see that here.
Its not as far alone as the lower end but it defiantly happening as well.
Lack of competition today does not belie there never being competition. I would argue that anti-trust should be taken against killing/buying your competition when it's still in the womb, see Instagram-v-Facebook, WhatsApp-v-Facebook, InstagramStories-v-snapchat