Bolt ran 19.19 in late(r) 2009, and 19.56 early in 2010, and still couldn't touch Johnson's 300m WR. When/if Bolt can run 30.5ish for 300m, then maybe, just maybe, he can be considered possibly in the neighborhood of 43-flat or under....until then, this is all just a pipe dream. And if he really said that (about sub 43) after struggling to a 19.79 with a slight tailwind, then he's completely lost it...out of touch with reality.
Bolt's biggest problem is his unbelievable talent....which enables him to train minimally, screw around, party until 4am and eat chicken mcnuggets, and still win championships(or at least it has until now)...but no way he gets the 300m or 400m WR without seriously buckling down for a full year of hardcore training. Johnson was a workhorse...far better work ethic and training ethic than Bolt.
My bet....no way Bolt ever gets close again....not even to the 300m WR.