10 million is pure hyperbole. Leaving aside the access issues, unless all those airlines apparently in a holding pattern actually start arriving one after another, then there's no evidence that the local infrastructure will ever be challenged.
If you look back around 18 months you will find interviews with Glyn Jones where he stated clearly that 5 million would be the maximum number the airport could handle. He was right then, and there's nothing on even the most distant horizon that changes that.
2018 has the potential to be a 'biggie' for SEN. But keep it real, please.