Lamentations is a despairing book and it ends on a note of uncertainty.
But you, O Lord, reign forever; your throne endures to all generations. Why have you forgotten us completely? Why have you forsaken us these many days? Restore us to yourself, O Lord, that we may be restored; renew our days as of old—unless you have utterly rejected us, and are angry with us beyond measure. (5:19-22)
Whoa. Basically, the Poet is saying that he knows that God is still in control and will stay that way forever, but the Almighty seems to be taking his sweet time letting the Jewish people back into his good graces. In fact, he's been completely silent during the aftermath of the destruction and the pleas of the Poet. He's not picking up the phone.
In the end the Poet has to conclude that it's totally possible that God might not want to have anything to do with his chosen people ever again. He can't be certain that God will save them. Maybe their misbehavior was just too awful. It's a pretty ambiguous and sad ending. It leaves you hanging—will he want them back? They've said their piece; the ball's in his court.