The "undocumented aliens" would be about 20% of the size of the legal population (that would be 6.5 million Jews, including settlers, and about 1 million Israeli Arabs, 1.5 million West Bank Palestinians). I agree, though, that it's so unlikely that Israel could get away with it that it wouldn't happen. I don't think it wouldn't happen for the reasons you think, though. Russia and Israel have strong connections and the Russians really don't care about the Palestinians and aren't likely to unless the Palestinians could buy sophisticated weapons systems from Russia (that's Russia's only interest in Iran and Syria; Russia would actually benefit from a war between the US and Iran as it would drive the price of oil back into a range that would allow Russia to keep balancing its books).

As for China, I think all they care about is the oil from the Middle East (they don't want that disrupted, Russia sees a benefit in selling weapons to Iran and also painting itself as anti-US, hence the opposition to US action on their part).

Let's be honest for a moment, also: most Arab governments don't care about, or even like, the Palestinians. They manipulate the Palestinian plight as a useful distraction from domestic issues, and that gets filtered down to the Arab street as Muslim solidarity (and it's at that "street" level that most of the anti-Semitism and pro-Palestinian sentiment is felt; a dangerous parallel to the "das ist für die Gasse" anti-Semitism of von Schönerer turning into the "von der Gasse" anti-Semitism of Hitler for the future if the Israelis don't make peace soon).

Ultimately, it is the fact that time is not on the Israelis' side in terms of maintaining peace with Egypt, Turkey and Jordan (or a quiet border with Syria) that is going to push them to need to normalize relations with the Palestinian Authority. The increasing democratization of the Middle East creates a situation in which Israel risks seeing the rise of demagogues ready to capitalize on anti-Semitic (I know, it's not the best phrase when talking about Semitic peoples) sentiment to get elected or re-elected. The cronyism of the Saudi kings may last a while longer, but in other states the sands are shifting, and that is a threat to Israel if it doesn't normalize its relations with the Palestinians (PA, not Hamas). Normalization would also hurt the positions of Hamas in Gaza and Hezbollah in Lebanon (though Hezbollah is likely to be very, very nervous either way when Assad finally falls later this year).

As for East Jerusalem, I don't think the PA has enough leverage to get it.