The finale of The Handmaid's Tale may have left viewers with more questions than answers. (Spoilers!) It ended much like it began, with Offred (a.k.a. June) sitting at the window in her bedroom at the Waterfords' home, waiting for something to happen. This time, however, something major did: a black van pulled up outside and men arrived in the house to take June into custody. Assured by Nick beforehand that she should just go with them, Offred was not perturbed by the uncertainty of her future. She seemed fine with whatever would happen to her — though there's no telling what might happen. The Handmaid's Tale ending left June at a crossroads. She could be free, or she could be in a lot of trouble.
When someone is taken away in a black van in Gilead, it usually means they will never be seen again. Though June had attempted to keep a low profile initially, as the series went on she grew bolder in her attempts to rebel and there were any number of infractions that could have earned her the ire of the Gileadan government. Not only was she helping the resistance by picking up a package for them, she also refused to take part in a Salvaging that would have seen Janine stoned to death for endangering her baby in "The Bridge." June's pregnancy will likely protect her from the worst forms of punishments, but she still broke the rules. It made sense for her to be taken away, just like Emily was episodes earlier.
But there is also another possibility, one that draws on the implications of the novel's ending. In the book by Margaret Atwood, Nick tells Offred that the men coming to get her are from Mayday and that she shouldn't worry about going with them. She has no way of knowing if she can believe him, but the epilogue suggests that Mayday did at least attempt to get Offred out of Gilead and she was able to record her story on the way to the border. It's still unknown whether she survived or not, but it makes the identities of the people in the van a little clearer.
The show could follow the path set by the book, but it could also diverge. Either possibility has equal weight and the show was much less explicit than the book when it came to Nick's explanation before the men arrived. But whereas the ambiguity of the book was never able to be expanded on in the decades since its publication, the Hulu series will be able to provide answers when Season 2 debuts. It may not be certain yet just what form those answers will take, but fans can rest assure that they're coming. It's just a matter of time.