Which one is correct?
There might come a day or it might come a day? And why so?
Thanks

Question

Answer

There might come a day, A day may come, If a day comes to pass that...- these are all subjunctive and refer to possibilities as well as hypothetical situations and not things as they are.

There might come a day when I no longer enjoy throwing rocks at road signs, but that day is not today.
- this option is the least severe in terms of how it is heard, I would use it for just about anything,

A day may come that you can't find your house key, so let's hide one behind this rock just in case. 
-this option sounds far more formal than the first as the word "may" is not particularly common in daily speech.

If a day comes to pass that you cannot walk, I will carry you.
-this option is the most severe and as a result I would only use it when the desire is to communicate the utmost sincerity.

Answer

Hey João,

''There + verb'' is considered to be a fixed grammatical expression used to introduce sentences in which a state, fact or situation is being announced. The most common sentence constructions regarding the usage of 'there' are:

1) 'There is/are' (there was/were; there has/have been...)
E.g.: There is a new place in town we should consider visiting.''
E.g.: There are so many trees around here! 
E.g.: There was very little money to be spent on a birthday gift.
E.g.: There were so many people talking in the room that I could barely hear the lecturer. 
E.g.: There has been a conspiracy to conquer our lands. 
E.g.: There have been too many people out on the streets demanding justice.

2) 'There may/might'
E.g.: There may be a solution to the problem!
E.g.: There might come a day when we shall be granted freedom.

3) 'There seem/appear'
E.g.: There seem to be several problems with the car.
E.g.: There appears to be a mistake here!

4) 'There will/is going to'
E.g.: There will be someone waiting for me at the airport.
E.g.: There is going to be a party this weekend.

Hope that helps!!!

Answer

It's "There might come a day...". There's no grammatical reason for it. It's just a fixed expression. But then again, there might come a day when I have a better answer....  ;-)