Yeah. My thought is that RISC-V has the potential to be very competitive in terms of compute/watt and compute/$. At the very least versus x86, but hopefully also with arm
We know there's already a lot of "built to purpose" RISC-V products ending up in embedded environments. When you have less obligations to a restrictive ISA grant, you can make something that fits your needs exactly.
So the business case is second-order:
* As has repeatedly been joked, fab companies who aren't locked to a captive/capricious owner (Intel) look appealing. It likely isn't about cutting-edge there, but the flexibility to handle diverse custom orders. Plenty of these products will be like "133MHz and a couple hundred thousand gates" that would be fine on 90nm or bigger.
* Firms that can move from "product" to "consultancy". There's a lot of brilliant work in existing ARM and RISC-V MCUs, but will existing firms be able to move away from "here's a matrix of features, order from the list" and into "Let us meet with your team, build a custom pick-and-mix and add a bespoke unit to meet your need for (smaller number than was historically common) product-specific MCUs?"
Otherwise, I'd imagine the cost of the mask set and validation to far, far outweigh any reduction in unit cost you might see from a custom chip. MCUs are already extremely cheap, especially if you're buying significant quantities.