Had the Jews lost the 1948 Arab-Israeli War, would Palestine have been established?

It most likely would have been. The word "Mandate" would simply have been removed from Mandate-Palestine.

There would not have been any Armistice Green lines in 1949 for Egypt and Jordan to fall back to in order to protect the remaining land for the Palestinians. That would have meant that Palestine would have been unbroken. That would have meant that the Jews would have remained a minority and would have continued to live as they had lived for 1000's of years amongst the Arabs. That would have meant that the bitterness of the Arabs being the majority ruled by the minority would never have existed.

The foreigners that came from Europe under the banner of Zionism would probably have been bitter that their dream didn't come true. That would have meant that the Haganah would not have been able to establish itself officially, which meant that radicals like Irgun and Lehi wouldn't have strengthened and wouldn't have festered in the land.

Egypt would not have lost their monarchy because the pretext of the military coup in 1952 was that the King was incapable of protecting his neighboring Arabs. That would have meant that the nationalization of the country by a zealous Army General would never have transpired, and Egypt would never have gone into the severe poverty it faces now under military rule.

That would have meant that Egypt would have remained a thriving country with open trade, and would have still had its alliance with Britain instead of the Soviet Union. That would have meant that Britain would have had a conflict of interest between the Balfour Declaration and one of its wealthy commonwealth nations, Egypt, which probably meant that complete and full support of the Zionist movement would never have come from Britain because of its support for Egypt as well.That probably would have meant that Britain would still be the superpower today since the 1956 nationalization of the Suez Canal would never have undermined Britain's world authority with U.S. intervention.

That would have meant that Palestine would have probably followed Egypt's political structure and framework as a thriving country with open trade, most likely under its own established monarchy. Such a young country would probably have required the protection of Egypt, which most likely would have meant that although it would no longer be a British Mandate, it would have strong influences from the commonwealth.

More importantly the question of land would never have been an issue because the majority ruling over minority is a common situation around the entire world.

Jews would have been able to trade freely, as they were in Egypt. They would have been able to establish their own religious laws within sub-communities for minorities, as it existed in Egypt. Egypt's Jewish population had entries at the royal court and were able to contribute to the nation's public transport, cotton industry, sugar refinery, banking, department stores, real-estate developments, agriculture, as well as having jobs as accountants, shopkeepers, teachers, and merchants. Palestine would have had a similar framework for the minority. Jews in Egypt were equal under the laws of property, contract and obligation, and were given rights to maintain their own religious rites and freedoms. Palestine would have had a similar framework for the minority.

If only the Jews simply asked to live amongst the Arabs as they did in Egypt, Tunisia and Morocco, rather than threaten to take the land instead.

In hindsight, the Jews are still at a loss even today, but not because of the Arabs... because of Zionism.