Imagine a scenario when all mobile phone companies finally decided to add a custom default bitcoin wallet to all of their devices as factory app. I believe that will further increase the adoption of bitcoin
What type of bitcoin wallets on mobile phones that are opt-in by companies. Mobile phone producers are centralized companies and their bitcoin wallets will very highly be centralized (custodial).
As we all know that 'Not your keys, not your coins', such wallets (if appear in the future) should be avoided. Not only because they are new released wallets but also due to their centralization and likely close-sourced wallets.