It will be ignored and will make no real difference. Christianity has always been based on expediency, not history. There's no such as thing as Christianity in any unified sense - there's a near-infinite number of reinterpretations of a core mythology which are used to support a bumper-sized catalogue of different moral and tribal positions.

This would be one more moral+tribal position. It might make for some awkward shuffling, but it's not going to persuade world+dog that it's always been just a bit of story telling.

An alternative use, preferable IMHO, would be to use the demonstration of this pre-existing "die and be resurrected in three days" theme to refocus at least some of the faithful on the moral and ethical teachings of Jesus as recorded in the many gospels and on the possibilities of personal transcendence they offer. The pathetic little miracle story enshrined by the Council of Nicea is intellectually and emotionally stultifying.  I strongly suspect it was grafted onto the teachings of a man who was talking about other and better things by "followers" who had lost any comprehension of what he was teaching and had other agendas to serve.

As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere."