If it makes any difference (although I fully agree it does not excuse past bad behavior), for the current gen devices, Kobo has partnered with iFixit to offer user serviceable parts and guides, including replacing batteries [0]. Although iFixit has had partnerships in the past that have fizzled, as long as user-repair is pretty easy, things like batteries are probably generic enough that they can be sourced even if Kobo doesn't end up sticking with it. If the screen fails though, then yeah, you'd better hope they have committed to maintaining stock of OEM parts, which, even with an iFixit partnership, is in no way guaranteed.
[0] https://www.ifixit.com/Device/Kobo