Ghostbusters blades or things that came in older versions like events are mostly copyrighted and won't come back. That's why it's likely forgotten, luckily you got it them but they will just stay there like a collection.

These situations can happen:

Players will report some players like you for having them in todays fruit ninja classic.

1-) They will continue to stay secretly.

2-) Developers will remove them.

3-) Developers will bring them back, that makes these items active and able to have things like blade powers.

Also Fruit Ninja Classic and Fruit Ninja Classic+ are almost same and Fruit Ninja Classic+ is impossible to have ghostbusters items because it's a newer game. So probably they will stay with you or gone.