I have had small (basically plugs) echinacea make it back from rabbit munching before, so you should be okay. Just get out the deterrents for a while until they get larger, at which point they seem to leave them alone... or there are more tasty things out there.

If you really think rabbits, get some cages over those plants. Slugs seem awful hungry this year to me...and they're doing quite a bit of damage on newly emerged plants for me ;( I don't like poisons...so I'm just letting it be.

Agree on those slugs! I know I don't have rabbits but many plant cuttings or seedlings that I prepped in the ground are gone. One day here, one day not (so it's not like a cutworm effect that seems to leave the stalk for you to witness the death of your plant in the next morning).

Crushed eggshells sprinkled around newly-emerging perennials will discourage slugs/snails--they can't crawl over the shells because the shells cut them. I save eggshells all year and when spring rolls around, the crushed pieces help protect my perennials, including hostas. I just toss the shells in a plastic bowl & use a potato masher to crush them.

As long as the OP's Echinaceas had healthy root systems, chances are the plants will send up new growth despite marauding bunnies.