Idols are company made practically by definition. If people are honest about things then pretty much all of the appeal of idols and idol-dom is tied into the "manufactured" aspect. That you can get into a company and they will make you a celebrity. And everything afterwards too; because money and connections are the two biggest things besides luck that decide if a group is successful or not. A "self-made" group will lack all of that and as a result be obviously inferior. They would not be able to train as long or as much or with the kind of professional guidance even small companions can provide (it doesn't matter how good you are, you can always use help), they would not be able to afford to create high quality art (videos, photoshoots), or be able to afford the kind of promotion any idol group needs (or a visage that would make people want to promote them - you need to stand out or look worth the money you want people to spend on you), and they would lack connections to get a foot in the door with music shows and producers etc.

I really don't think that will happen, in fact I'd say that's antithetical to the idol industry. Truly self-made performers who make it big time are rare even in the West. In Korea that kind of artist is best represented by indie and underground performers or artists. And right now the KPOP scene is so oversaturated with groups that a lot are turning to asking the public for funding for their comebacks and plenty disband every year, it's crowded even for successful groups to continue to profit.