At the moment it would be a very sensible move, given the affection of Apple users for compact phones and the cannibalization of XS by other models. In addition we must consider the excellent sales of XR, which together with XS Max has exceeded sales by about 4 times. And meanwhile iPhone SE continues to run out of stock whenever Apple puts it back on the market.
The message is very clear. It is useless to produce smartphones that are halfway between pans and handhelds. If you really must do it, it is a good idea to offer them at advantageous prices and not above the € 600 threshold. The Apple lineup for 2020 will therefore include a 5.4 "iPhone 12, a 6.1" XR3 and a 6.7 "Max 12, all in 5G. Sensible and hopefully winning move, even if for many already significantly behind the competition.