Whether it is ARM or something else I think x86 as an ISA is going away at some point. The licensing overhead is just too much to sustain. IMHO something RISC-y is a better solution technically anyway, at least as long as general-purpose CPUs rely on electrons. Heat limits mean that clocks can't be pushed any higher than around 5Ghz, so to get more compute power per "chip" (die) we need more cores. CISC instruction length is a handicap in that situation. It is also easier to design RISC CPUs hardware-wise. ARM is in a good position to take over because it is already well-known on the server, mobile, and embedded side(s) of things. Linux, BSD, and even Windows can already run on ARM processors. Even ARM has licensing fees associated with it however. Not nearly as much as x86, but enough that people already over-sensitized to such things from having to deal with x86 might over-react and consider starting from scratch to be a desirable situation. That might give an opening for something like RISC-V. There's already a debian linux port for RISC-V, and development/experimental hardware to run it. We'll see.