I used to pay for a photo editing software and used it for years. Then they got bought out by another company and the SW languished. And there was no easy way for me to migrate my photos away from it. Today I cannot even run the version I bought - incompatible libraries, etc.
Photos will last longer than the SW used to edit them. Don't lock them in.
Neither LR nor Capture one lock in your photos though. The edits will be locked in I suppose but I don't see a way to not lock them in. Are you saying that Dark Table somehow doesn't lock in your edits?
At least LR does not lock in your edits; I'm fairly certain Capture One doesn't either. You can export either XMP sidecar files or DNGs with the edit history bundled in along with the RAW data. LR's centralized catalog is just an SQLite database, I believe, but I don't think the schema is documented publicly.
Genuine question, are those edits usable in another app though? I.e. even if the XMP notes that I used a range mask with some color filter, if capture one or DT aren't capable of this or aren't capable of reading the sidecar files, isn't this a de-facto lock-in?
DT is open source, so even if it is abandoned, you have hope of still getting your edits. You have hope that if the original authors decide to abandon the project, someone else will take it on, etc.
Photos will last longer than the SW used to edit them. Don't lock them in.