Don't worry. People were using Reddit and Digg at the same time for years until the migration was actually done. That'll also happen with Reddit and Fediverse this time
That’s a very good point. I remember that transition. Same is happening with Twitter -> Mastodon. Slowly more people are coming over and spending less time on Twitter as the content gets less and less (and grows on Mastodon). It takes time but it does happen.