True, segmentation is already happening with users choosing apps based on geography, age, and sometimes by social group. It’s possible to target and win over a select group of people if you have a compelling feature or an experience that’s geared towards their needs. You just have to decide who you are focusing on.
I can easily imagine a future where people switch between three messengers, one for general communications with acquaintances and family, one for work, and one for their social circle. Many already do this with social networks.
chat is network effect, so a chat app needs to answer "which network of people" if the creators about traction?