I hope the signal will lead to the black box and the mystery will be solved. There is not guarantee here though, because it's quite possible that they may not be able to locate it due to the depth. It is also possible that the battery may die, which would make it even more difficult.
I think a newly found signal could bring this mystery to an end. Even though the batteries were only supposed to last for a certain amount of time, I think it is very likely that they will last longer than expected. It just becomes more difficult for the families not knowing what happened to their loved ones. We owe it to them to keep investigating.
The finding a new signal, possibly that of the 'Black Box', is not going to bring the Malaysian airliner mystery to any type of conclusion anytime soon. Even with the new signal the search area for the missing plane is still more that 5,000 square mile. With working depths exceeding 15,000 feet it will take more than 60 days for each pass of the target area. Without luck it's going to take a lot of time to find the box, if ever!
No, the possibility of a newly-found signal will not bring an end to the Malaysian airliner mystery, because it is another false hope. Recently, they said they were sure the plane is at the bottom of the Indian Ocean. But they are not really sure of anything. They will never find that plane.