People often look at the SE from the perspective of a phone that is cheap to buy, but I think it's important to look at it as a phone that is cheap to make. In hindsight, the previous SE were all geared around phones that saved Apple money on the production, distribution, and support side. Yes, they have to have a value proposition on the consumer side, but ultimately the cheapest iPhone with a relatively recent CPU (not because the CPU matters, but because long term support by iOS matters) is very compelling to many consumers. Even if the screen quality is low, even if the battery life isn't great. This describes the past several SE.
I'm age 40+ and a large number of my peer group have SE, not because anyone recommended it to us, but because it was the natural place to land for people with a mortgage and kids, who don't really care about advanced features, and certainly don't create content.
Anyway, from this perspective I think there's a chance that the SE takes the mini form factor. There's less physical material in a mini (they can save money on the chassis costs alone), and you can fit more of them on a pallet (saving money on packaging and shipping). At $600 or whatever the mini was not a great seller, but at $400 as a base model phone I bet it does just fine.