In some sense they already have an ISA, denver. But I'd say the odds of this deal falling apart leading them to making SoCs that (primarily) run an ISA besides

In some sense they already have an ISA, denver. But I'd say the odds of this deal falling apart leading them to making SoCs that (primarily) run an ISA besides Arm is exactly 0%. If they eventually do do that, my baseless speculation is it would be because of demands of automotive customers. If it was decided that risc-V was a selling point for automotive, then maybe. (Proprietary ISA? I'd guess never.)