All those roads in London I have a right to ride on. M4 motorway I do not, nor have I ever had. This distinction is what makes you initially silly, but now tedious, diversion a straw man argument.
I've done it out to Junction 6
Knobbers, old son, you're winding yourself up something chronic.
I'll summarise
The evidence is (check this very forum) that segregation increases cycling deaths per million miles
There isn't space for the kind of segregation you propose
When space is found (CS2 - at the expense of a bus lane) it's nowhere near as successful as bus lanes (CS7)
Segregation is uncivil and makes walking and bus travel less pleasant
There's no strategic benefit in mass cycling - CS7 is at capacity, and yet the contribution it makes bears no comparison to the humble bus.
The scheme for the Embankment (were it to happen, which I doubt) will ruin a wonderful bike ride - and I take that personally