It’s not a bet at all. Sony already has hard numbers on gamers with mixed physical and digital libraries, how many people are using discs to watch movies, etc.
The vast majority of customers have heard zero of this news and aren’t principled in their purchases or easily compromise on them, so it’s safe enough to assume that anyone who primarily buys physical games but has bought digital before will still fully transition over out of necessity.
Only Sony knows these numbers, but whatever they are, they’re one-sided enough that Sony is already killing off ways for them to backtrack, and Xbox isn’t far behind.