The future of 32-bit Linux

I suspect it's more tied to the manufacturing process than with licensing: Cortex-A73/A53 based SoCs started out as high-end designs on 14nm, which can be refreshed into a 12nm or 11nm product without doing a complete redesign.

Cortex-A75/A55 usually started out on 10nm, with a possible shrink to 8nm. It appears that this generation is not economical yet for a small low-end to mid-range chip like the Snapdragon 66x, and the Snapdragon 460 looks like a co-design of that, if not the same chip in a lower bin.

I would not expect the Cortex-A73/A53 generation to be nearly as long-lived as the pure A7 or A53 versions, but instead get replaced with A75/A55, A76/A55 etc as the respective designs make it from high-end to mid-range chips. There are already Snapdragon 690 and Exynos 800-series mid-range chips based on 8nm A77/A55 that fit this description, while Mediatek and Unisoc already tend to use newer cores on older processes.