I mean, for the record, its as Franky said. They are a Yonko crew now. Killingham, Gunko and Super Sommers have country ending powers and if Luffy's group didnt exist with Loki then Elbaph would be gone.
We also dont know how these 3 are relative to Shamrock, and what he is relative to Gorosei or Shanks himself
Could these 3 alone face Yonko? Probably not. But if all 8(?) were together with Shamrock, who may or may not be relative to Shanks, then its possible.