Loyalty is just one factor. There's customer satisfaction (which iPhone still carriers a high mark), and also actual sales and revenue. Since only Apple knows about the actual numbers, anybody else talking about it is just speculating at best.
What imo Apple should be doing is making their iPhone upgrade program available in all markets. Apple is at a huge disadvantage in some markets (eg. in some markets, the XR is more expensive than the Galaxy S10). If Apple cannot change their pricing points to match their actual intended positioning (due to regulations, tariffs, taxes, etc), then the next best thing is to have iUP available in all markets. Most people will definitely balk if they have to pay $1000 right off the gate for an iPhone XR (yes, in some countries, that's the starting price of the iPhone XR, not the advertised US$750), but they probably will be okay paying $40 a month with a guarantee of getting the latest iPhone every year.
Apple, just like many US companies, are still seeing the market from a US-glasses. Imo they need to start thinking about what non-US iPhone users want. They definitely started with dual-SIM support (although the decision to go eSIM is dumb).