Do I think that will ever happen? 99.9999999999% sure it wont, but i'm also 99.99999999999% sure unicorns don't exist, a t-rex wont in front of me this second etc. etc. For me to believe in a god, anyone of them, i'd need irrefutable proof which is basically 'god' talking to the whole world at the same time. If I heard the voice of god by myself, i'd check myself into a psychiatric ward and if someone told me they heard the voice of god i'd suggest they do the same thing. Also you say the second coming, but theres hundreds of people that claim to be the second coming of jesus christ every year. And you assume it would be christianity that would prove itself, specifically the paedophiles and mass murderers, why couldn't hinduism be proved correct?
If Shiva, Vishnu, Ganesha etc. etc. Appeared and start destroying, maintaining and creating would you abandon catholicism and worship them?