It was neither: it's only crime was to be non-trendy. At the time that development on 68K stopped, RISC chips were the "in" thing and while both the Intel Pentium and Motorola 68060 were clever designs that essentially built some CISC decoding logic on top of a RISC-like core (which combined the best of both worlds), 68K ended up dying because the higher-end systems that it got used in either died off or switched to RISC CPUs in order to check off the proper box on the sales brochure. x86 was spared death simply because the market it operated in wasn't as glamorous to begin with...
