We'll need to wait and see what the future printing will say. Because currently, dropping it as a free action and using a bonus action to swap places does get around having it up. If they decide that it disappears immediately when you finish using Echo Avatar, then it won't work. If it still follows the "end of your turn" rule, then it should still work.

I think you'd be able to switch places with your echo up to 1,000 feet away once you get the Echo Avatar ability. Since it states that there is no action required to end the effect, and an Echo is destroyed at the END of the Knight's turn, you could end the Avatar effect, then teleport immediately as a bonus action on the same turn before your Echo goes away. I believe this gets around the issue of not being able to teleport using your Echo Avatar.