Fair enough, but Apple Silicon is not a specialist chip in the way a SPARC chip was. It's a general purpose SoC & SiP stack. There is nothing stopping Intel being able to invest in SoC & SiP and being able to maintain backward compatibility while providing much better power/performance for a mobile (including laptop and tablet), product strategy.
They could also just sit down with Microsoft and say "Right, we're going to go in an entirely different direction, and provide you with something absolutely mind-blowing, but we're going to have to do software emulation for backward compatibility and that will suck for a while until things get recompiled, or it'll suck forever if they never do".
Apple did this twice in the last 20 years - once on the move from PowerPC chips to Intel, and again from Intel to Apple Silicon.
If Microsoft and enough large OEMs (Dell, etc.), thought there was enough juice in the new proposed architecture to cause a major redevelopment of everything from mobile to data centre level compute, they'd line right up, because they know that if you can significantly reduce the amount of power consumption while smashing benchmarks, there are going to long, long wait times for that hardware and software, and its pay day for everyone.
We now know so much more about processor design, instruction set and compiler design than we did when the x86 was shaping up, it seems obvious to me that:
1. RISC is a proven entity worth investing in
2. SoC & SiP is a proven entity worth investing in
3. Customers love better power/performance curves at every level from the device in their pocket to the racks in data centres
4. Intel is in real trouble if they are seriously considering the US government owning actual equity, albeit proposed as non-voting, non-controlling
Intel can keep the x86 line around if they want, but their R&D needs to be chasing where the market is heading - and fast - while bringing the rest of the chain along with them.