For an ironic family crest, I would like to incorporate the motto "Things could always be worse" or a similar Latin saying.
Starting from Terence's (Adelphoe III, 2, 46)
Peiore res loco non potis est esse quam in quo nunc sitast
Literally: In a worse place the thing cannot be than it is now.
Not so literally: Things cannot become any worse than they are now.
⋯ we can construct:
Peiore loco etiamnum res posset esse.
⋯ or, if you like it simpler:
Peior etiamnum res posset esse.