The whole discussion RE: solo films not making as much as the main team films merely shows that the X-Men are greater than the sum of their parts. Wolverine works better in the context of the team and solo X-Men films, regardless of who they are or who plays them, will come to that similar conclusion.
Hugh's Wolverine on its own - acceptable BO returns.
Hugh's Wolverine in a team of X-Men - better BO returns.
Now, as we've said over and over (and over), the X-Men films shouldn't be dependent on one star to boost the box office but that's been entirely Fox's fault and considering they failed to learn that lesson over the course of 16 years, I have little sympathy for them. Every movie has breakout character successes but the fact is the core X-Men team has several characters who could fulfil that role. Gambit, Rogue, Storm... I could go on, all have potential to be big successes - but they've made zero effort to elevate those characters beyond the half-hearted larger Storm role that Halle Berry had to fight for and was so far removed from the strengths of the character that it was irrelevant anyway.
We should not have got to the point where, this many years down the line, Fox can't enthuse an audience to come see a movie without a large Wolverine role.
And we, as fans, keep playing a game of "Well, the next film will give us Storm and Jean and Cyclops the way we really want them" but it's 16 years, we should've had those characters the way we wanted them from day one.