lmao bands in K-Pop are a lot- I mean -a lot better than what we have in the west. They're all trained to know how to sing, dance, function in a group properly, know how to live together with at least four other people, all this for a good one year, likely to be more. That's why most of them have lasted together for years at a time, pulling out chart-toppers in Korea one after another, aside from the quite short-lived "mainstream bands" here, like N*SYNC, or the Backstreet Boys, or the New Kids on the Block.
Also, the music industry is a lot busier there than it is here, with bands and artists debuting each year, as well as everyone of them pulling out a song or an EP every few months, so there's no reason to fear drastic changes in musical development.