It was a project that wasn’t Die Hard that then, eventually, shifted over to Die Hard.”
McClane reportedly began life as Die Hard Year One, which would have used the Die Hard prequel comic from BOOM!
Taking an idea that was not originally meant as a Die Hard movie would have been very, well, very Die Hard, with the franchise having done this multiple times in the past.
It could well be that the studio decided not to move forward with a Die Hard movie that lacked Bruce Willis at the center, with di Bonaventura previously explaining the difficulty of trying to continue the franchise without him.