OBS is heavily architected around plugins, many of the built-in features including FTL output are plugins, so even if it is removed it would likely be possible

OBS is heavily architected around plugins, many of the built-in features including FTL output are plugins, so even if it is removed it would likely be possible to turn FTL support into a separate plugin that users can install. For reference the FTL code is in the plugin called obs-outputs (part of the main OBS repo). The only real limitation I know of is that it is likely not possible to make the UI exactly the same as it currently is.