Intel's x86 killed the RISC workstation with Windows compatibility and price per MIPS. Intel then matched and surpassed AMD on AMD64 counting on its own size and on the complexity of building a very fast 64-bit x86.
All factors, Windows compatibility excepted, are on ARM's side this time. Of course Intel has survived bad situations before, but this time I am not betting on them.
1) Power usage on low end chips. ARM will be ahead of x86 on platforms below the smartphone for the foreseeable future, and on smartphones for another generation (2-3 years)
2) Manufactures can customize ARM to build SOCs. I can't see Intel allowing complete customization like that, but I'd expect them to ship some competitive SOCs themselves.
It's simpler for ARM to adopt performance enhancements that make the core more complex than for Intel to adopt simplifications that make their cores more power efficient without losing performance.
All factors, Windows compatibility excepted, are on ARM's side this time. Of course Intel has survived bad situations before, but this time I am not betting on them.