I wouldn't mind that as a feature to personalize your Ghost further, but you have to consider: 1. The amount of time and money it would take to get new voice actors to record new dialogue for the existing game and all future DLC, especially if they get big celebrities to do it, so you're talking 10 years worth of voice-over work per actor. 2. I don't think that many people would actually pay for a feature that minor, most would rather it just be added in with the DLC or as a free standalone pack, so I don't think they would make enough profits for it to be worthwhile.