While I don’t expect there’s going to be any meaningful impact on Reddit once the dust settles, I do think this will bring a lot of new users to the Fediverse.
Reddit losing a few hundred thousand users is a drop in a bucket given their user base, but it is a significant boost for us.
Most likely, and this works well because it allows time for server capacity to grow and for wrinkles to get ironed out gradually. Fediverse would have a hard time absorbing millions of people all at once, but a gradual trickle of users allows things to grow organically.