Conflict with USA changes everything for any nation in this world.
Once USA canalizes its whole capabilities against a foreign country, that country fights from this point on for survival. Seen at the Iranian art of survival campaign, Turkey would immediately re-configure whole foreign policy and create problems for USA to disperse the USA of canalizing her capabilities at Turkey.
There would be formed quaint alliances and some non-state actors would be born that target US interests.
There could be further implications like: Iranian-Turkish alliance, maybe that alliances would be such serious in strategic depth that others join in seeking to destroy the US world system.
Turkey has a high reputation in Muslim world, a reputation for voicing out Muslim interests on international level. There is an audience Turkey will receive sympathies from.
In your scenario, where USA takes side of Israel, this would be regarded as Jewish-Christian alliance targeting yet another Muslim country.
I don't know if Turkey would receive open support from Muslim countries, but I think yes, especially from Pakistan:
Pakistan?Turkey relations - Wikipedia, the free encyclopedia
Whilst the Arab Muslims fought the Ottomans in its ending days, the Muslims from the Sub-continent send money, food and material to Turkey.
Turkey always assisted Pakistan openly on dilomatic level in its wars with India and send military spare parts to Pakistan.
If Turkey and Iran form a goal-intended alliance to fight USA, even without with Pakistan factor supporting Turkey, that could be pretext for World-War based on religious lines with no puppet regime in Arab countries resisting the pressure form streets.
Now coming back to reality:
Turkey, unhindered by the Persian-Arab and Israeli-Arab rivalries, can do things for the United States in this region that Israel simply cant achieve. In short, Turkey is the more valuable ally to Washington than Israel.
Turkey means it when it says its relationship with Israel will not go back to what it once was. The two countries will likely maintain relations, but Israel will not be able to rely on Turkey as a regional ally. The United States, meanwhile, cannot afford to prioritize Israels interests over Turkeys. In this geopolitical climate, Israel lacks the luxury of options.
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Turkey's strategic depth was always defined by military aspects in Cold-War.
Turkey sits on one of most valuable geographical assets, this will continue to be so. NOW the difference is, Turkey adds to her strategic depth also the soft-power things like economic outreach, and socially influencing a bunch of weak countries in the neighbourhood receptive for a "Plan C". "Plan A" is Arab-Jewish conflict, "Plan B" is Arab-Persian conflict.
"Plan C" is economic integration of Sunnite looser-countries behind Turkey, to make together the shift into a position of "having a say" in near future's world.
