right now, TrinityCore supports MySQL only – which is completely fine. Especially in scenarios with larger player bases a rdbms is essential.
I do however think, that TC is also very popular in "solo player" or "LAN party" situations where one wants to play around or leve on his own, or just play with friends and family.
Would implementing SQLite support for such "local" applications of TC be benificial? And how hard would it be to rework the TrinityCore code to support SQLite?