I have no idea how important Israel is to American Jews. I did a little homework and found some articles arguing Obama was more a friend to Israel than Bush in some instances (Bush opposed bunker busting bombs and the so-called Iron Dome while Obama supported/approved both plus military aid to Israel was reported as being very strong). It is hard to say who really supports Israel more between the two parties. If you believe the Republicans are stronger Zionists then the inference is a Jewish vote for a Democrat is putting America first. But the party differences concerning Israeli policy may be so slight that a Jew can vote Democrat and still be a Zionist. I'm not sure the shift to the right would ever occur. I see the Jewish vote as similar to the white hipster vote for AOC. The civil rights sympathies are too ingrained now.
Omar stepped in it when she said AIPAC was buying Congress. Then of course when she said a nice smile does not cover up for murder. She's a loose cannon on deck.
@NJlonghorn has commented on this before, and he could probably give you a much better explanation than I could for two reasons. First, he's Jewish himself. Second, he likely knows more Jewish people than anybody here. Accordingly, he knows 100 times more about what Jews think and why they vote the way they do than I ever will.
Nevertheless, here's a
link to how Jews have voted over the years. They've been a pretty reliable Democratic constituency for a long time - even gave decisive preferences to McGovern and Mondale. However, once the neoconservatives gained prominence with the GOP (and the GOP became solidly pro-Israel), Jews started to give at least some support to the GOP. That is probably why Reagan and Bush did fairly well with Jews (at least compared with previous Republicans). However, they broke strongly for Bill Clinton and stuck with him and Al Gore (both of whom were pretty solidly pro-Israel), but that support softened some in the last 15 years.
I think most Jews are more nuanced than the AOC white hipsters. Most hipsters are pretty dumb when it comes to politics and are generally a bunch of hosers. I've literally never known a dumb Jew in my life, and they're generally decent folk. I'm sure there are some dumb ones and bad ones out there, but none have crossed my path. As for their voting, my guess is that Jews probably follow many of the same patterns as non-Jews. Obviously, it's a pretty superficial analysis, but secular Jews are probably more socially liberal, and though they probably care about Israel, it's probably less of a priority for them. More religiously observant Jews are probably more socially conservative (or at least moderate) and put a higher priority on Israel. Like other voters, the secular ones probably lean Democratic, and the more observant ones probably lean GOP with plenty of exceptions. Since the secular outnumber the more observant ones by quite a bit, that means Democrats dominate the Jewish vote.
Could I see Jews turning to the GOP in big numbers any time soon? No. Could I see their support for Democrats softening a little more in 2020 if people like Ilhan Omar keep talking like David Duke and Joseph Goebbels and getting only tepid resistance from the Party? Yes. Could it be enough to impact any states? Maybe enough to make it harder for Democrats to flip Florida. Nowhere near enough to flip any other states that have substantial Jewish populations (New York, California, New Jersey, Illinois, Massachusetts, Maryland, etc.).