I'm not sure I'd describe Coreboot and Libreboot as "having momentum", at least not at the level where anyone is thinking about them while making PC hardware?

For RISC-V, the biggest issue seems to be a) actually designing a full chip with all the necessary peripherals (assuming just scaling the core bits is comparatively easy) and b) motivating someone to invest the fab time. I guess many potential commercial users will continue going with ARM, just because it is proven, designs and knowledge are available, ...

Before laptops, I'd expect more microcontroller-type stuff, where customization and license costs probably are more relevant, less complex periphery is used and the necessary fabrication capacity is more easily available.