When Bigg Boss season 8 officially ended, 5 contestants from the main season, entered the spin-off season Bigg Boss Halla Bol.
Now I think the same format would be followed here. 5 Contestants from Bigg Boss OTT would enter the main season of Bigg Boss 15 along with other new contestants, and those would be most likely :
1. Divya (Most likely the most popular contestant, and even though Bigg Boss and Kjo hate her, she would provide ample amount of content).
2. Pratik (Again a popular contestant and Bigg Boss too is in his support. He again has a lot of scope to provide entertainment).
3. Shamita (When outsiders are getting a chance, nepokids shouldn't be left behind either. She's useless as a contestant, but Kjo has his blessing on her, so would Salman).
4. Nishant (Smartest player in the house but still failed to make a good fanbase. Probably because of his non-existent personality. But he has backing of Colors and Bigg Boss so he's definitely entering the main house).
5. Neha (Nobody likes this bajre da sitta. But she still has blessings of Bigg Boss and Kjo, who keep on saving her from nomination and elimination. Probably because she has scope of providing alot of drama in the house).
If makers decide to take six instead of 5 contestants from Bigg Boss OTT to Bigg Boss 15, then the sixth baggage would obviously be Ramu kaka Raqesh Bapat.
Since I believe he too has strong connections to the makers. But if this guy has any self-respect left, it would be better if he gets evicted instead of going ahead through crutches of makers. Because as much time he's in the show, the bigger fool he would look.