>>508304149That's not an "out" to Iran if it was a failure.
Things like that don't just get shat out overnight, those bombs take a lot to build, hence why there's barely any.
Although the replacement for it, missile-backed and much much lighter, is arguably a superior idea, so even if it was a failure I don't think it will get used much if ever again.
Far better to take them apart and re-use the materials in newer bombs.
Gravity bombs are just not worth it due to the absurd weight requirements and flight requirements to do any damage.
A missile with the same materials will be able to reach much further.
Admittedly you can still construct an underground bunker complex that can direct missiles away if you design it properly, like making lots of low / no density channels for a potential missile to travel down and away from a bunker in to a sacrificial cavern, but that's a whole different discussion.