The organ in Tarragona's Cathedral was completely dismantled and a new organ will be built by Verschueren Orgelbaw. That's all the information I have about the new organ to be built.
The existing pipe work and other parts of the organ, including the soundboards, have been kept for the future use, in case the decide to build a new organ using that material or reconstructing the Aeolian organ the they belonged to.
The cases in the chapels are the pipes for that organ. There still are some more pipes, stored somewhere else in the Cathedral, that belonged to the organ. Those were removed/discarded by the extint OESA organ builders when they did the last refurbishment.
I hope this clarifies your questions.
Santiago Munoz
