Dungeons will be the next to die, then they will probably start dropping support for last-gen consoles on bedrock. Java literally can not die though. Even If bedrock is more popular, Java is the easiest to code with because it only needs to work with Linux, macOS, and Windows 10. Bedrock currently has support for 4-5 phone OS's alone plus all the consoles and windows 10 so it is much harder to make compatible. Plus, almost all of the competitive players are on java as it is way farther ahead as far as servers are concerned.