Abrams confirms there will be no mention of Midichlorians in TFA:
http://www.slashfilm.com/the-force-awakens-midi-chlorians/
This is a huge relief for me. Since (as the title suggests) the nature of the Force will be a prominent theme in TFA, I was deeply concerned that Midichlorians would have to rear their stupid heads once more, but this proves that Abrams and Kasdan don't feel the least bit constrained by the nonsense established by the PT.