Klarna is so well integrated into so many ecommerce stores it might be a challenge to get a retailer to replace them. Paypal are also doing very well out of BNPL. The real play is in traditional bricks and motar stores, if Apple can do BNPL there, then that's the USP.

Apple is just another player, they have a premade customer list. It's getting the otherside of the market place to see the benefit.

I don't have an iPhone, so I won't be changing any time soon :)