Yes, it is something we were thinking about. As for now, we decided not to go down this route because the way we promoted Pro teams to Elite ahead of ECL 5 was similar to today's decision. As we did not announce any changes beforehand, we didn't want to implement any last minute solution.
Now, this is a case we weren't prepared for when we developed the divisions framework, so this left us with a small surprise. We all agree that Elite should always feature the very best teams, and to accomplish this, we will think about carrying out a mini tournament between the remaining teams in case a team cannot participate in the relegation games. That needs to be added to the rules first though (together with everything else division-related), so expect an implementation for ECL 6.