This. There are 3 HMs we have seen evidence for but still can't use in the field: waterfall, dive, and rock climb. Feebas could become obtainable by any one of these 3, and I think it is very likely that we'll need the super rod. Honestly I wouldn't be surprised at all if we wound up finishing the story arc we're currently on before Feebas/Dratini becomes available because of the super rod limitation.
As far as what we'll be getting next episode? A few dive specific event pokemon around reborn, an event pokemon in Ametrine City, maybe something to do with Simon and Tara, and I'd hazard a guess at Clamperl, Chinchou, and Relicanth being the main wilds down in the depths.