Hard to tell, with ARM's incredibly vague language, whether MVE is a vector extension, or just a packed SIMD extension.

Added: I'm sufficiently insulted by how tedious they've made it to download related documents, that I'll leave it to somebody else to care enough. [0]

[0]: https://pages.arm.com/introduction-armv8.1m.html

I wonder what level of concern RISCV raises internally at ARM. Are they panicked, or just adjusting strategy in a more routine way?

It seems the moves from Western Digital would be concerning to them.

Though I suppose on the other side, there's not yet any credible/volume RISCV general purpose CPUs yet (just MCUs), so maybe they aren't yet scrambling.

Given their public reactions, I imagine they see it as an existential threat.

https://www.theregister.co.uk/2018/07/10/arm_riscv_website/

ARM has done an incredible job legitimizing RISC-V.