I never pay these types of "e-readers are doomed" articles any mind. If you're reasonably tech savvy (and everyone on this forum probably is), you know how to convert any e-book format to just about any e-book format. And I'm sure that e-ink will continue to be used for years to come, and that we'll be able to find older e-ink devices for sale online in the unlikely event that they're discontinued.
I'll always have a Sony 505 or something similar to read my books on, and I'll always find a way to convert them.
So I'm not worried.