No Gambit in X-Men 3 reports that Gambit won’t appear in X-Men 3 afterall:

Today, Ralph Winter (one of the film’s producers) confirmed to The Xverse that there is no appearance by Gambit in X-Men 3 — but that it might be included in “the next one”. This indicates that despite any possible plans to end the series with a trilogy, people involved with production are open to future X-sequels.

Thanks to ‘FamkeFan’ for the heads up.

Source: FamkeFan