Hope I got it correct from my last lecture about aviation... The question of landing rights can be a tough issue. For IB, it all depends from the bilateral agreements between Spain and the third countries IB flies to (this does not affect European and all other flights which operate under an open market/open skies agreement).

Let me make an example to clarify: if Spain and Country X have an agreement that regulates flights between the two countries and this agreement includes limitations based on nationality (i.e. only Spanish and Country X carriers can fly these routes), then the takeover could become a problem. If more than 50% of IB is taken-over by BA/LH and therefore IB becomes a British/German company, it might lose the flight rights that are sealed in this kind of agreements (since IB wouldn't fulfill the nationality requirement anymore). The Spanish government would in this case have to renegotiate a new agreement with Country X (and all other countries with similar agreements) to avoid the loss of such rights for IB. Technically, I think it's a question of introducing the so called 7th freedom in the bilateral agreement (i.e. the right to carry passengers between two foreign countries without continuing service to (or originating service in) the carrier's own country). Hope some of the experts can help on this last point.

This is exactly what is happening in Switzerland too. LX hasn't officially been taken over by LH yet (shares are being held in a trust), since the Swiss government is negotiating new bilateral agreements to prevent LX from losing these rights when it becomes a German company.