Things no one needed for a thousand Alex. Past a relatively short range you need a spotter and advanced targeting. If you have both anyway, you might as well use something we already have that is more accurate. Additionally, I doubt wars will be moving away from the close quarters affairs like they are today. You don't have enemy armies hunkered down in one location that is vulnerable to such weapons. You have enemy forces that are either very mobile or inside of structures with potential non-combatants. Depending on the region, you may have enemy command groups in hidden bunker like features (such as caves) but you will notice a trend of people just not fighting in a way that would make such a weapon useful.