In Fiddler on the Roof, during the Disney Acid Sequence of The Dream, when the chorus pass one to another about the arrival of Lazar Wolf's late wife one of them says "Why not?" I always thought it was just meant to be a funny line... until I heard it again and thought about it... and remembered this whole sequence is meant to be Tevye inventing a dream to his wife, so this is actually him saying Throw It In!.
I figured out years ago that the Fiddler can be interpreted a couple of different (not entirely mutually exclusive) ways: 1) He's an actual member of the village with an odd hobby, 2) he's purely symbolic of the village and how it deals with "TRADITION!" If seen as #2, his appearances become significant. When he is first seen (title sequence), he is tottering on the roof, which, as Tevye explains, is like their way of life through their traditions. When he next appears, he is no longer on the roof, but rather on the ground! Mind you, Tevye is drunk at this point, but perhaps this was a vision from God! If that is the case, he could be saying it's time to let go of some superfluous traditions, but without losing their identity as a people. When he appears at the end, its Tevye's way of saying to himself that they will continue to be the same Chosen People, even if he's willing to bend tradition pretty heavily by this point (the fiddler has no roof anywhere in sight).
Of course the daughter of a milkman can't marry a butcherit's not kosher to combine milk and meat!
Thirty years is plenty of time for them to end up following Tzeitel's parents to America at some point (and hopefully Chava and Fyedka, who go to Krakow, would make the same decision, as Chava and their children would still be considered Jewish under the Nuremberg Laws). Poland had issues with anti-Semitism even before the Nazi invasion, and so perhaps they would have found another reason to pack up and leave.
If they could afford to.
Even if they did escape to America, the rest of the Jewish community in the film almost certainly perished in the gas chambers, or, if they were lucky, emigrated to Israel. There is a sort of added poignancy to Fiddler when you realize the story of Eastern European Jewry ultimately ends thirty years later. The End of an Era.
And even the not-terribly pleasant Orthodox Russians who expelled the Jews from Anatevka would get to experience World War I, the Russian Civil War, the Holodomor, the Great Terror...and then Hitler's armies would arrive.
Also, Tevye has five daughters. The first falls in love and goes against Tevye's tradition and morals. The second falls in love and goes even further against his tradition and morals. The third falls in love and goes so far against Tevye's tradition and morals that he basically disowns her. The play ends before the fourth and fifth daughters can fall in love but following the pattern and especially with the fact they're going to America where things are less formal... you just can't help but feel this either won't end well for Tevye or he's going to essentially lock them up.
From Tevye's POV it's easy to imagine him on his deathbed circa 1950, not only having lost all his Old World relations and maybe a U.S. Armed Forces grandson or two in the war and the Holocaust, but with his New World ones, already ultra-assimilated by his standards, moving to the suburbs where there are only Reform congregations...
For the record, in the original story, one of the two other daughters kills herself after her lover abandons her, and the other marries a rich jerk who just wanted a beautiful trophy wife but doesn't love her at all.
A close inspection of Fiddler's dialogue says Tzeitel and Motel have been married for two months. The next scene shows them with a baby. No wonder Tzeitel wanted Motel to hurry up in proposing...
But that means Tzeitel would have already been seven months pregnant during the wedding. You would think that everyone will have noticed. If not, everyone would probably know about it anyway thanks to Yente.
Tevye says the line about Tzeitel and Motel being married two months in the Act 2 Prologue. The baby isn't there until Act 2 Scene 5. Time passes between these scenes. Perchik leaves Anatevka in the middle of II-1 and at the start of II-2 he has already been arrested and convicted, for example.