Future of App developers is Bright because its market is growing regularly, New players coming to the market many offline businesses are switching to online version due to the cheap Internet in India and High competition. Also, apps need to updated regularly as per the requirements. More than 50% time of total time spent on digital Media is On Mobile apps, With new Technologies such as ML and AI demands for App developer, will increase. 

As far as salary is concerned, You will wonder that the average salary of a Mobile app developer is more than 1lac USD.