Im likely closing my instance soon due to costs and im sad my comments will disappear and remove and context and replies to them breaking many threads. Is it possible to preserve the comments someway or maybe migrating the comments to a another instance?
If your comments have been federated to other instances, they will be there until they are deleted locally. If someone clicks on your user profile, they will get a DNS error if the domain is no longer there. Images in the comments pointing to you instance will be broken too. Nothing terrible actually happens.
Migrating accounts a la Mastodon is not happening soon in Lemmy.
My advice is: Go on and save some money.