A lot of the terminology here is confusing, as we haven't put a lot of effort into choosing good names.
I'd suggest using "interpreter" for tier 1 including the specializations and "jit" for tier 2.

This leads to some odd terminology like "jit interpreter" for the tier 2 interpreter, but I think it is clearer overall.

I think a lot of core devs and the wider community think that what we currently call the "jit", i.e. the machine code generation pass, is where the performance gains will come from, but they will come from all of tier 2. The earlier passes will be vital for good performance.

Also, maybe add a diagram like this:faster-cpython/ideas#557 (comment)

This is excellent, thanks.

I have a few (minor) suggestions, otherwise it looks very good.

One typo to fix, otherwise looks good.