I would not say this is on response to riscv. First of all, ARM was one of the very few vendors not supporting before but mainly due to their co-processor model

I would not say this is on response to riscv. First of all, ARM was one of the very few vendors not supporting before but mainly due to their co-processor model. Second, the reason arm in giving in now is due to new performance requirements for v8-m due to crypto and ml usecases.