Iran with a nuclear bomb would dominate and spur Egypt to also develop a bomb. Although the obvious objective target is Israel, Iran's real goal is domination of the Middle East. Iran could not attack Israel with a bomb since Iran would then be destroyed. Iran is not suicidal; they would prefer to have Hamas and Hezbollah do their dirty work.
47 killed in clashes between ISIS, Syrian rebels near Turkey border, monitor says (Reuters)
from the article: Muslim Brotherhood lawmaker: Arab Spring headed to Iran