Community support and growth
Developer communities surrounding the very popular MERN stack technologies are quite perse and growing on a regular basis. With lots of people continuously using, fixing, updating, and willing to help grow these technologies, the support system will remain strong for the foreseeable future. These technologies will continue to be maintained, and resources are very likely to be available in terms of documentation, add-on libraries, and technical support.
The ease and benefits of using these technologies are already widely recognized. Because of the high-profile companies that continue adoption and adaptation, and the growing number of people contributing to the code bases, providing support, and creating resources, technologies in the MERN stack will continue to be relevant for a long time to come.