In an interview with iF Magazine, X-Men scripter Simon Kinberg talked about the Wolverine solo film starring Hugh Jackman.
Regarding whether there was any pressure on him knowing that there was a spin-off movie coming after X3: "Wolverine doesn't exactly come after X3 so what happens to him is not terribly relevant to his own movie," Kinberg said.
"We did talk about a couple of characters that they wanted to save for the Wolverine movie spin-off. I can't tell you who they are, but there was really only one we wanted to use for X3, and they said they're not going to have a big enough part to risk losing them for Wolverine. Sabretooth will be in there, but I don't know in what form. I think his relationship with Wolverine is under explored.
"I like X1 a great deal, I thought the tone was fantastic and thought the X-Men were great, but I was a little under whelmed by the Brotherhood in that movie," he told the magazine. "I thought the secret island lair and Magneto's plot were confusing to me, and Sabretooth and Toad were not as strong as Mystique. I like working with actors who have inhabited their characters for a while, and I welcome their input. Hugh has lived with Wolverine for five years and he knows this character better than anybody. He knows him better than Chris Claremont or better than Avi Arad, and certainly better than any of us working on this film. Hugh was also a producer on this movie, and we worked really closely with Hugh on Wolverine. The most conversations that I had with actors on this movie were with Hugh about Wolverine and Famke [Janssen] about Phoenix. They both are incredibly smart people who had a lot of intelligent informed questions about the characters. I would say the most input about Wolverine came from Hugh and not the studio."
You can read the rest of the interview here.