Change doesn't happen overnight
These processors might be effectively obsolete because of RISC-V but there's still a lot of them out there and there will be plenty in the production pipeline. Its the same with actual MIPS processors -- the switch will occur over a period of years because of product life cycles.
Integrating this architecture with the GUN toolchain would be a first step to phasing it out since it would free a lot of developers who would have been otherwise engaged in developing and maintain a proprietary toolchain to move to new work. (...and given the depth and sophistication of the GNU toolchain it doesn't make sense to go it alone anyway, you're far better off contributing work to the open source project)