The mystery of the force will return once again in the new Star Wars films, according to J.J. Abrams, who says the hated midi-chlorians -- the needless biological explanation of the force introduced in the miserable first prequel -- will not be mentioned. Presumably they're still there inside, but not talked about lest they ruin the retro vibe.
Confirmation of the binning of the midi-chlorian myth came from Abrams himself, who was answering a series of yes/no questions on the red carpet of a Mission: Impossible screening. Here's the full interview. It's not particularly serious, but is only 1:47 long so you might be able to make it all the way through without getting bored or checking your phone:
The midi-chlorians were the reason given for the existence of the force in The Phantom Menace, which had happily been a thing in the original films without any explanation. They turned having the force into something similar to having Type 2 diabetes, changing it from a dreamy mystical energy thing into a kind of space chlamydia that could be measured and, presumably, treated.