John Owen-Jones is a wonderful Valjean, and my personal favorite. When his honey timbre and gentle falsetto meet for bring him home he brings the house down! I personally think Valjean is his best role as a character actor, even better than the phantom. The role of JVJ is like a second nature to him, he broke records as the youngest Valjean in history and he has been performing it since 1997 I believe.
Re: being "booked with another project." At best the new musical we hope that John will star in is unfinished and behind schedule. The concept album for An American Victory was supposed to have been released summer of last year-- there has been no explanation about the delay, and I do not know of a new projected release date for the album. Multiple members of the cast have sadly also been changed, the great Ruthie Henshall and great Hugh Panaro are no longer attached to the project. As far as I'm aware John is still interested in the show, but it looks like we have a long way to go. John might very well want something more concrete in the meantime like Les Mis, An American Victory may never even be made. Though I hope this is not the case. I would like to see him create a role in what sounds like a very serious drama.
John has already expressed his interest in returning to Broadway, though it is a little unlikely it will be in Les Mis. I think there are some arguments for why he should be considered. His reputation is larger than it was in 2007 when he first came, he is a very beloved actor, and his 2010 tour was very well-received. If Earl Carpenter is going to perform the Javert this would be an opportunity to recreate the chemistry he and J.O.J had in their previous show, they were both great.
Lets go back to Hugh Panaro too. He and J.O.J I think have a similar vocal range, I consider John the finest tenor voice on the West End and Hugh the best we on Broadway have to offer. If not John, why not Hugh then? He is a very capable character actor, had experience with the role both in 2008 and 2013, the later of which he won an award for. He brings the excitement and prestige of a familiar face-- a recent phantom and broadway veteran with decades of experience, yet we might also avoid the matinee idol salaries. He's had time to rest from the phantom and may be ready for a fresh start. He sounds like a sensible choice to me, and would sing the score divinely.