I'm a bit disappointed by this decision.
Mobile devices who support GL ES 3.1 are recent too. They will probably support Vulkan. I can't imagine Vulkan to be so restrictive.
Why not keep GL ES 2.0 for " old " devices and add a Vulkan choice for PC and recent devices ?
GL ES 2.0 seems pretty decent for all 2D games and devices who can't support Vulkan probably haven't a sufficient hardware for beautiful 3D games .