If the aliens are here on earth and have- as some maintain- been observing us and intervening in our affairs since forever- it will, when the story finally breaks- involve a rewriting of history and an adjustment of our view of things comparable to, in fact considerably more disruptive than, the shuffling and kerfuffling brought about in the mid-19th century by Darwin and Russell and the geologists. I read somewhere, on some website or other, that the Vatican has declared itself willing and able to baptize any aliens who show a desire to embrace the One True Faith- which is remarkably broadminded of it. But can you see the Greys and the Nordics and the Reptilians lining up to take advantage of the offer? No, me neither.
Personally, I think we're overdue for a paradigm shift. The current one (we're just accidents of Nature, all alone in the Universe) is beginning to smell distinctly off.