> 2. ... x86 becomes a co-processor, just like how discrete GPUs are handled ...
That's become my hunch too in the transition to ARM, with Apple producing a SoC that integrates an entry level x86, with usual 2 upgrade options. Eg the next product line would be:
$1599 -- Dual-Core 1.5ghz A14 + Dual-core 1.2ghz x86
$1899 -- Quad-Core 1.9ghz A14 + Quad-Core 2.4ghz x86
$2199 -- Quad-Core 2.5ghz A14 + Quad-Core 2.7ghz x86