I'd be very surprised if it actually happens. Italy constantly announces this and nothing happens, and I'd bet good money on this being nothing more than a few groundworks that go absolutely nowhere. It's not even the Mafia, but the fact that Italy is using some very creative accounting to try and build this bridge by assuming that it's part of defence spending. Then there's the fact that the various criminal families in that part of Italy will have strong reasons not to let the bridge happen, as it keeps the region backwards.
This is nothing but Salvini's cost of taking a backseat to Meloni, and I wouldn't be surprised if the end result is nothing but groundworks so that he can pose there in the next election by claiming that it's 'being built'.