The only thing that can make them worth something would be if the project team decides to resume working on the abandoned project. Otherwise, your bagheld tokens remain worthless and as useless as "ay" in okay. You aren't the only one bagholding in expectations that the tokens will worth something in future, especially with those who are whales in such projects. I've not been able to delete some of the apps whose tokens I hold a lot too. I guess it's the emotional thing of "what if the project comes back to life tomorrow?" kind of situation.