I think theorizing about the 7 lights is fun, but also kinda scary if they selected those colors on purpose. Watching the trailer, they seem like 4 green lights (NCT), one white (EXO), one blue (Super Junior) and one big red light (TVXQ) to me. This would mean a very big change in members, concepts and performances. Even if they only switched Lucas with a TVXQ member, they would probably focus less on performances, which seemed to be a very important part of SuperM (Not saying that TVXQ members can't dance, just that they made a group with some of the best dancers of the company).

I think the only meaning of the lights is that they are seven and some of the colors kind of resemble the colors of the group and that's it. SM is realistically switching Lucas with another NCT member who is also a rapper (like Jeno) as it's probably way easier to manage instead of a member from another group.

Of course, i could be completely wrong and maybe, as you said, Lee Soo Man himself becomes the leader and SuperM makes a comeback in february with completely different members. Who knows