Good odds Sabireen/Islamic Jihad will eventually get a black market nuke and hide it in one of the tunnels making a big glassed crater if and when Israel ends up sweeping the area.
Iran likely obtains a nuke from North Korea. Detonating one in a religiously historic city is a no go. It could be put on a rocket, but expensive risk of getting shot down. If Israel's army gets concentrated for some reason preferably in rural area such as outside Gaza that would be a tactical vulnerability.
