Said this in the Gorosei matchup threads but as opposed to the other Gorosei, Garling feels like a character that was created for a specific propose and not simply for the purpose of being just a strong opponent for one of Luffy's allies or subordinates to defeat hence why I've always felt that it only really makes sense for him to fall to either Luffy or Teach narratively. Plus the fact that he's the warrior god of defense gives off the feeling that he'd be at the forefront if Marijoea is ever attacked. So what are the chances that Garling is currently facing off against whoever is attacking Marijoea (i.e. potentially Blackbeard?)
Keep in mind that Oda loves his parallels.
Teach is Rocks parallel so chances are that similar to Rocks killing an admiral Teach also parallels that feat and kills someone in a similar position. Moreoever Garling is connected to God Valley and apparently scared WB so there is very interesting plot line there that Oda could end up exploring.
Just food for thought.