Sqlite should be around for a while, and since the source is around it should be possible to compile it in the future. I don't know how stable the file formats are, or if you'd have to do regular migrations.

Text-based formats in my opinion still are a better bet for really long-term storage, since I think they are easier to recover from partially-broken states. (E.g. if you give me an sqlite file with a few bytes broken, I don't know how how to recover that. In a text-based format I can fix it by hand if necessary, or modify my tools do deal with it). More complex formats can be derived from them and used as caches: e.g. for a large text-file archive, you might want to have a full-text index in some database format for faster querying. As long as that index is fully generated from the base dataset, its stability is not as important.