Between people shifting from pc to arm-powered phones and major data-center users doing their best to cut costs this is shaping up to be a tough decade for Intel.
Hindsight makes Itanium look like even more of a disaster, when that energy in that era should have gone into evolving the x86 platform for the future. Without AMD doing what they did (x86-64) I wonder where Intel would actually stand in the server market today.
Keep the x86 decoder front end that they have now. Add another one for the better ISA. Add another mode that kicks the CPU into that ISA. Current x86-64 OSes already generally support two architectures: x86-64 and i386. This would just be a third one. Then everything could move to the new ISA incrementally, and legacy software could keep on working forever using the legacy decoder.
I'd guess that the x86 ISA is no longer enough of a bottleneck to justify it. Throw enough transistors at the problem and perhaps it doesn't matter anymore whether your ISA makes any sense.
Not only is it possible, but it has been done. Look up the Transmeta Efficeon. Note that it's not RISC-like but VLIW (which I like to think of as "the next thing after RISC").
If Intel Cpus use a Risc like architecture nothing would prevent static translation to it, which was not feasible for Transmeta cpus. The x86 software layer would then only be there to preserve backwards compatibility.
IBM was pretty close to cutting off most funding to future development, and they just closed the factory in Minnesota that made the servers. They are pretty much the last survivor of the Unix wars.
There are major customers using this stuff and scaling up, but the industry as a whole is shifting to scale out. There might be a good story here with POWER8, but can you trust that the platform will be around?
....which they moved to Guadalajara, Mexico. Given the money they put into Watson, I would expect they keep the POWER machines.
It's not something they spread around, but from what I recall from a Q+A with IBM engineers the Watson prototype was developed on AMD xSeries servers, and only moved to pSeries machines late in the development before the Jeopardy! matches.
The business growth for power was displacing PA-RISC, SPARC and Itanium... IBM is the last man standing, but are competing against whomever is supplying AMazon, etc for barebones x87. In the IBM line, it's jammed between commodity x86 and high margin zSeries.