...to Madrid must happen soon! Andalus was the latest rumour.
Upon the marriage of BA and Iberia, MAD will look very unlikely. People seem to think that, like with the AA move, it will be better for the regions. Maybe so, but only in the form of shuttle runs to LHR.
UK-(BA)-LHR-(BA/IB)-MAD/BCN-(IB)-Spain will be the general pattern if you wish to travel with Oneworld.
Unless one of the LCCs are looking that is...