If the Sirius/XM merger proved to be a model, initially both companies' technology would be kept running, independent and separate. The company would be rebranded with a common name but you'd either get your programming from Dish's or DirecTV's set of satellites (the Sirius and XM satellites are in two incompatible orbits).
Eventually, you'd go down to one set of satellites and one system of transmission. In the Sirius/XM situation, they have chosen to go with XM's satellites. That transition hasn't happened yet.
That said, I suspect that part of the significant return on investment for such a deal is leveraging the satellite bandwidth from a combined organization as well as transmission facilities/resources. That would bring substantial operating cost reductions like most other tech mergers.
The changes to make that happen, however, would involve some major modifications to a wide range of components in the ecosystem.