ARM has always had a strong incentive to promote more ARM platforms. Apple doesn't really change that, and they still pay royalties per chip, even with a perpetual license on the ISA AFAIK.

Simply having less x86/Intel around can't hurt. Competitors are going to want similar battery life. This effectively means ARM. Also, there's now ARM chips being used in very capable laptop, desktop, mobile, and server applications. All of this reduces cross-architecture friction (cross-compiling, different memory models, etc).