I personally cannot see any near term replacement for what SQLite offers. In my world, SQLite became the way in which I now manipulate a scope of structured data on a single logical disk. I mostly view it as a very reliable and friendly layer on top of basic file IO which also happens to be compatible with virtually every computer on earth. I can copy a SQLite database out of an embedded microcontroller environment and directly open it on my x86_64 workstation, edit some values, and then copy it back down without any fears of compatibility issues.