It may happen but not only because of Bitcoin adoption but also usd printing and inflation. It's not going to be a fast process, something like that can take over a decade.
It's really a realistic projection because if we count that at least 50% of all people in the world will want to own at least a few satoshis we'll have to be at 1 million value, there's no other way. There's not enough coins to supply the world and this will have to make them scarce and extremely valuable.
If that happens and usd is still worth anything, on chain transactions are going to be very expensive (1 dolar per byte, minimum fee)
Lightning and off chain transactions are going to be really needed, and on chain transactions are going to probably be used just by banks and whales.
By then we'll have ways to transact outside blockchain. Nobody is going to try to include every single small purchase in the blockchain.