[wren6991]

...although you could certainly implement a Jazelle-style "branch to x86" instruction if you really wanted. It's fine as long as you come up in RVI mode.

Unfortunately you would not be able to repurpose the LSB of jalr targets as an "x86 bit" à la Thumb because the standard requires you to ignore that bit, though of course you could enable that behaviour with a custom CSR.