none of the investors coins will ever be burned, the amount you have now will not change, only the total circulating amount will be reduced.

Also, while a coin burn has been confirmed in Q1 of 2018, the specific mechanism for accomplishing the burn has not yet been specified. We don't know if they'll just remove a whole bunch of them at once or burn slowly per transaction, however Justin has stated that it will be similar to Ripple's method of burning a small amount of coins per each transaction, but "smarter" than their method, so we'll see when the details are revealed.