So it replaces a standard iphone and an ipad mini.. Samsung and other makes have tried to make these a thing since 2019, they all have massive compromises, durability issues, and cost substantially more
They really don’t side from cost , Durability is no more at risk as any other phone if you take care of them.
Foldables are a thing and sell well enough for brands to release them every year. They don’t replace slab phones but certainly is a market for them.
When Apple comes to market will certainly boost sales