I honestly think it's too late for Parler. I think folks have gone to GAB as an alternative and are liking what they are seeing much better, so no need to go back to Parler when/if it ever sorts out its problems.
With each passing day they are falling farther behind the exodus boat.
If Parler and GAB were smart they'd work together to form a "freedom approved" ecosystem. There's a pretty big market segment there for the taking.