I am suppose to go to Mexico, but I might need to cancel my flight.

I know my ticket is non-refundable, but if i cancel my flight is there a way to get a credit for a future flight?

If I "change my flight" can i picket a completely different destination several months in advance?

If I can't get any compensations, is there any reason to cancel my reservation? I don't like the idea of united not compensating me and reselling my ticket to someone else to make double the profit.

Thanks