So the decoder is like an emulator. If so it would theoretically be possible to provide a different ISA and have it execute by the cops as well. Not saying it would be fast, or practically possible due to how locked down it is.
Transmeta tried that approach, but it wasn't enough of a competitive edge for it to prosper.
Transmeta couldn't bring their product fast enough to the market because Intel was suing them.
It had nothing to do with the quality of the product itself.
Then NVidia re-used their design on ARM as Project Denver.
Is this kinda what thumb mode on (some) ARM chips is?