Domhnall Gleeson is by far the most mysterious role in the new Star Wars judging by current rumours. Either his part is very small, or it is a secret they're working hard to keep. He is an actor very capable of being a lead, a caucasian male who could play a Skywalker (and looks very much like Ewan McGregor while sporting a beard), and while I admire the casting of John Boyega and Oscar Isaac, are you saying that Disney is going to make a multi-billion dollar investment in a series know for a white audience with a black brit and a latino as the male leads? I would like to think so, honestly, because I hate all the racism there is, but I don't believe the world is there yet. And people who have so much money, they aren't the ones who takes risks. I've seen enough comments on John Boyega for it to be anything but a very daring choice. Having both Boyega and a white caucasian lead however!
More so, Star Wars-film series being a series about the Skywalker-family - bets are there at least are two new Skywalkers in the new trilogy. That leaves Daisy Ridley and Adam Driver as being likely candidates, and rumours about Adam Driver sort of makes that unlikely (there's been widely agreed that he is a villain from an aristrocratic family).
I can see John Boyega, Daisy Ridley and Oscar Isaac as being the leads for Episode VII, but I'd bet one of them is going to do a Qui-Gon and we'll see Domhnall Gleeson as the Luke/Anakin of Episode VII-IX.