What happened to Dani in Danny phantom?

In the final episode of Danny Phantom, Dani is taken away by her captor, Vlad Plasmius (Vlad Masters). They escape into a portal which opens to an unknown destination. She is not seen again for the rest of the episode nor in any later works in the "Danny Phantom" universe. Because the series never received a complete final season, viewers were left unaware of her ultimate fate. Fans continue to speculate whether she and Vlad are stranded together in another dimension forever, if something tragic befell her at Vlad's hands, or if there is hope she might return someday.