According to the Wikipedia article Inspiration Mars Foundation:
Their website became defunct by late 2015 but it is archived by the Internet Archive. The Foundation's future plans are unclear.
A spokesman for NASA stated that "Inspiration Mars's proposed schedule is a significant challenge due to life support systems, space radiation response, habitats and the human psychology of being in a small spacecraft for over 500 days", but that "we remain open to further collaboration as their proposal and plans for a later mission develop". John Logsdon, professor emeritus at George Washington University's Space Policy Institute, also found the short preparation time-frame wanting, saying that it is "totally implausible" for a mission to be launched in 2018, although the"Plan B" mission might be possible "if the stars align".
I'd like to as if there any other information about this mission or concept, or any possibility that it might be re-proposed in the future.