Traditional websites are never going to become obsolete. As the technology evolves the existing websites will also improve to provide a better user experience. Mobile apps and websites are completely different verticals from the user’s perspective but in reality they are quite similar, and both provide programmers with high-level, object-oriented coding. If smartphones are gaining popularity, that doesn’t necessarily mean the computers are out of service. In my opinion web development and mobile app development is not comparable to each other. If you are concerned about your career as a website developer, you must keep up with the industry trends.