Few folks with drones will be successful in making a decent amount of money from real estate photos and short videos. Sure some folks will do it as a sideline to earn extra money, a small number of people will be able to earn a decent living from this market, and a very few number will be wildly successful. The barrier to entry for this market is too low: obtain a part 107 license, buy a phantom 4 drone that takes acceptable pictures, a bit of post processing, enough training to take a decent pic, and online distribution. For less than $5,000 and within 3 months anyone can call themselves a drone photographer and go into business.
A sure sign of oversaturation of a market is when people exhort newcomers not to give their services away. I saw this happen when digital cameras hit a low enough price point that lots of would be professional photographers rushed to get into wedding and portrait photography and there were plenty of craigslist ads with people willing to shot a wedding for $100 or less.
Remember that a drone is simply a digital camera that can fly. No special knowledge is needed to take basic real estate photos and videos.