To me the Midichlorian concept is more inclusive than the Force was in the classic trilogy. In the classic trilogy, all we knew was that Luke was strong in the force because of his parentage. Back then, the idea that Han had a shot of being able to use the Force was all but non existant.

Now that we have the Midichlorian concept, which includes all life forms, it's not such an outlandish suggestion to think that Han would also be able to learn the ways of the Force, even if he didn't have as much natural ability as someone with a higher concentration of Midichlorians.

Hey Tiptup, did you see my response to your post from way back?