This is what Bryan Singer had to say on the matter.
"I think there would definitely be room. I think it would be a very exciting thing. This universe has to establish itself first, but that would be a very interesting and fun thing."
Bryan Singer also claims that he is not scared of having an X-Men movie without The Wolverine.
"It's a completely different film. Xavier and Magneto are important characters as well. It's just a different X-Men film. I obviously love the character, but you can't not do it just because he's not in it."
The Wolverine was released July 26th, 2013 and stars Hugh Jackman, Tao Okamoto, Rila Fukushima, Hiroyuki Sanada, Svetlana Khodchenkova, Brian Tee, Hal Yamanouchi, Will Yun Lee. The film is directed by James Mangold.
X-Men: First Class was released June 3rd, 2011 and stars James McAvoy, Laurence Belcher, Michael Fassbender, Bill Milner, Kevin Bacon, Rose Byrne, Jennifer Lawrence, Beth Goddard. The film is directed by Matthew Vaughn.