Yeah, 125 GB blu-rays are not happening. They are not cost effective at all, if they used them instead of doing 2 or 3 dual-layer blu-rays the cost of physical games would increase above $60 for the first time in over 15 years, and gamers clearly don't want that to happen. Remember, all games are installed now anyway, so you'd only need to pop-in multiple discs when you go to install a game, after that you'd only need to pop-in the "play disc" when switching between games, like you do with the multi-disc Red Dead Redemption 2. Also, Sony is likely going to keep using standard dual layer blu-rays so that they can incentivize people to switch to digital, where the profit margin is higher for both Sony and the publishers of the games.
Obviously BC is the best of these rumors for me, as I don't care about VR and 125 GB blu-rays are not happening.