No, as part of our renaming, Hobby dynos and Hobby-Basic Postgres will be automatically changed to Basic plans. No action is required on your part. When they change to Basic plans, your app will restart. The impact is similar to any other user-initiated release.
If you use hobby dynos in your app.json files, please update them to basic at your earliest convenience.
See our blog post and the Low-Cost Plans FAQ for more info related to our new plans.