How Much Should Developers Invest in iPhone Duo?

I maintain many apps. Watching Apple’s six iPhone Duo sessions, I kept thinking about how many layouts I’d now have to test. Closed, open, partially folded, rotated, sharing space with another app. The challenge is making those transitions feel natural while actually using the extra screen. To me, this is one of the biggest changes to iPhone app design in years. But how many people will use it? Bloomberg Intelligence estimates around 14 million Duo sales in its first 12 months, equivalent to roughly 6% of an annual iPhone market of 241 million units. These are forecasts, with slightly different reporting periods. I’m more bullish. I think 6% is achievable, and 10% of new iPhone sales is possible with strong demand and enough supply. That would mean roughly 24 million devices. My optimistic scenario, not the analyst consensus. Samsung offers an interesting comparison. In 2024, foldables accounted for over 20% of its phone volume above US$1,000. That includes Fold and Flip, and only…