If we used to make that flight,if the flight number still is IBxxxx,and it is sold through IB's web as IB flight operated by... then i'd say it is our production,taken away.
I understand your frustration but these things need to be looked at in a very business orientated way.
For example a route operated by a carrier may not return suitable revenues when compared to the same route operated by another carrier with a substantially reduced cost base.
Revenue generated per passenger mile is subject to a multitude of variables which equate to the aircraft operating cost per passenger mile. If the operating costs of one carrier exceed the revenue generated then the route operates at a loss. Unless the operating costs can be reduced the route will lose money. Operating the same route with reduced operating costs (aircraft lease, fuels, oils, catering, cleaning, Cabin Crew, flight crew, navigation fees, landing fee, airport taxes etc. etc. etc.) where the passenger/cargo revenue exceeds the operating costs and the route makes a profit.
Hence giving loss making routes to a 'cost low' solution makes business sense. If the changes at Iberia allow those routes to be operated in profit then perhaps they will be re-instated, somehow I doubt it. IB is obviously concentrating on primary revenue routes, including cargo, and dropping loss making routes on short/medium haul where the LoCo competition is making revenue generation difficult.
By reducing the workforce, the wage bill, the aircraft leasing costs etc. IB stands a chance of making a profit from those primary routes. It needs to start from a solid foundation though.