She will leave the idol industry and move on to acting which I think is something she's very passionate about and has dreamed to do
I think she'll want to dive into acting more, she will have a successful acting career, she'll leave SM but will remain an Red Velvet member
She will go solo, I think her solo career would be very successful, I would say the concept she'd be going for is a darker more bold concept in comparison to Red Velvet's concepts, she'll stay with SM
She already had went solo but I think she'll continue to make more music as a soloist, I think she'll be very successful, I think she'll continue to release ballad-ish songs but she'll try new things like R&B, she'll stay with SM
Joy-
Like Irene, I think she'll leave the idol industry and move on to acting, I don't think she'll want to continue as an idol, she will have on overall successful career, she'll stay with SM
Yeri-
I think she'll become a producer and actress, since she seems to enjoy writing songs I can see her becoming a producer, as well as an actress, I believer she has the potential to be an actress, I think she'll stay with SM
overall:
Since Red Velvet are an Sm group I don't believe they'll disband but I do think they will be on a long hiatus