So the vocal and rap line will be making the song while dance line will be performing it and appearing in the MV. On stage performances; vocal/ rap line will sing/ rap and dance line will dance to the song. But instead of as a backup dancer; these people will be part of the group. This can also solve all the problems people have with members who dance well but cannot sing as well or vice versa.
This idea came to me after i was watching this bollywood song and lot of NCTzens were commenting that the flute sound in favourite is similar to the music in the start of this song. Unlike kpop/kdrama; in bollywood; actors are supposed to be good at dancing as well while singers only need to excel in singing.
The singer of this song was 68 when she recorded this song which is quite impressive because most woman soloists career only last up to around 35 after which they are not as popular anymore.
in this way kpop groups can have really good singers and also strong dancers.