I heard some rumors that Kylo Ren may be Jacen Solo but I don't think he is Jacen Solo however I believe that Kylo Ren will have some sort of connection with the Skywalker but will not be Jacen Solo. For one, Jacen Solo's influence to the Dark side was brought about by Lumiya(The Light Whip Lady), whereas Kylo Ren is suppose to be drawn in by whoever Serkis' Sith Character is going to be. Then they said that Kylo Ren's injuries were from a crash and had to go on prosthetic support by which he has that in common with Lumiya; Jacen Solo never had prosthetics, even after his fight with Luke and Jaina. Jacen never used a crossguard lightsaber, just the typical single blade. Then again the stories can change but looking at things now Jacen and Kylo Ren are two different characters. What are your thoughts on them?
Even if he was, it doesn't mean he's gonna be the Jacen of the old EU. So it's rather moot anyway to bring that up, because if he is, it's only going to be by name.
Kylo Ren has been the rage of the sequel trilogy thus far. With his Crossguard lightsaber and his identity still a mystery, he's open to speculation by any starwars fan around. I think this thread is far from useless.
From the looks of it, they are gearing towards Jacen Solo being Kylo Ren but their backgrounds seem different from The New Jedi Order. From what I heard Han Solo gets killed by Ren, Jacen never killed his father. Jacen killed Mara Jade, Luke's wife but he never killed Han Solo. Plus Han Solo was alive after Jacen was dead.
[SPOILER - highlight to read]: http://starwars.wikia.com/wiki/Montross and [SPOILER - highlight to read]: http://i.imgur.com/rh6XojX.jpg are supposedly the same person.
When the concept art first leaked, the image tagged Montross in the original file name. This, of course, could be completely false, but it's what was posted. Could be the same name on a new character, but it's still a nod.