Yeah, even if it stays non-nuclear, another Iran-Israel war would be a Bad Thing. Even with the US pimping out the Israeli military. Because there is plenty of not-Iran-or-Israel area in between them, and how do you think the nations in the middle would react to either nation launching an invasion force through there? How about fighting a war there? I can't imagine it would end well.
It would also be weird. Syria is in a civil war, so they wouldn't officially enter the conflict. Turkey likes the US but dislikes Israel, so it would either be on Israel's side or neutral. Jordan and Israel have issues to say the least, so Jordan would probably be on Iran's side. Egypt is a wild card, popular consensus there is really against Israel but breaking the peace treaty would lead to an immediate loss of US aid. Israel, Iran, and Neutrality are all possible. Tunisia is too far removed and would probably remain neutral. Libya now has pro-US sentiment and doesn't directly conflict with Israel, so it could end up with Israel or neutral. Iraq has waning US influence but also anti-Iranian sentiment and could well end up on Israel's side.
But here's the weird one. Saudi Arabia. No official channels with Israel. Doesn't care for Iran because it is the world's largest population of Shias, and while the Wahhabists don't care much for Jews or anyone who isn't a Wahabbi Sunni they can't stand Shias. Thus would begin the most surreal alliance in history as Israel and Saudi Arabia team up to take down Iran.
Iran is actually making all the right moves for itself. Getting nukes is one of the best things it can do for itself.
Getting nuked by Israel isn't a good thing for your country.
We however, even though we ABSOLUTELY do not want Iran to get those nukes, won't do a single thing except look at them really angry.
Except for planting car bombs on their nuclear scientists and implanting state of the art virii into their nuclear plants. Don't you remember all that stuff?
Historically speaking the most likely eventuality is that Iran getting nukes will actually stop the Iran-Israel wars.
Yes, because everyone will be dead.