I was the starter of the
original thread regarding image retention on my late 2014 5K. I have since taken it in several times for the issue, and three displays plus a logic board later mine still does this, slowly worsening. I'd like to try one more time to get it fixed.
Depending on the severity of your case (it's hard to tell from the photos) if you're still under warranty you can take it in for a display replacement, but there's no guarantee the issue won't just come back even after then.