The Arabs in 1973 were not interested in the complete destruction of Israel? Really?? Assuming that the Israeli military is truly trashed (lets forget Samson for the moment) What keeps the combined Arab armies from occupying Israel? What stops the Palestinians from coming back and evicting Israelis from property that may (or may not) have been owned by any particular Palestinian family in 1948. While some Arab leaders may have been cynical about the "wipe out the Jewish state" propaganda from 1948 onwards, as well as what went on before 1948, the vast majority of the average Arabs in the street were good with that idea - and exactly which Arab leader is going to risk the mob turning against him for "saving" Israel. If the partition plan of 1948 was considered unacceptable by the Arabs (and the "Israel" that would have been created was marginally viable for a number of reasons) what would be an "acceptable" Israel. Even assuming you had a few blobs allowed for Jews can can bet most of Israel would be occupied and very likely either become "Palestine" or "temporarily" administered by the various Arab governments "pending" a Palestinian state. The most optimistic scenario is a small demilitarized Jewish state with all (or almost all) Jews expelled and property confiscated from any territory Israel loses.
The Israeli government and people see the above as the reality. Whether or not you or I agree with this is irrelevant, this is how the government of Israel and most Israelis see things. This is why Israel developed nuclear weapons and why the "Samson option" is discussed. As I and many others have stated, simply vaporizing the Aswan Dam would destroy Egypt, perhaps one or two other targets might be hit but maybe not. You could expect the capitols of any Arab states (other than Egypt) that are actively attacking Israel to get a nuke, and Arab formations that are worth hitting and are far enough from Israel population centers get hit tactically. Hitting Mecca and Medina would, IMHO, only be done in a situation where this is truly a strike for revenge not to salvage a status quo ante bellum.
Again, my feeling is that strikes against Russia would not be performed as part of this mess unless the Russians were actively involved. My guess is that the Israelis might let the Russians know that, sure the USSR can slag Israel, but it will cost them several cities in Southern Russia/Ukraine/Crimea and do they really want to make that trade. F-4s on low level one way missions can do this.
OTL Sadat was interested in regaining Arab pride and making the Israelis give back the Sinai. HOWEVER if you had the sort of overwhelming military victory you had here, going for more was certainly in the cards. Almost for sure Assad, and many other Arab leaders would be willing to take as much as they could. As for the Palestinian, their position on Israel was clear,
Bottom line, if the Arab armies do breakthrough and threaten core israel/complete defeat, nukes fly.