AMC Networks has taken full control of BBC America, a decade after it acquired the first half of the venture. Paying just $42 million for the remaining 50.1% stake in BBC America, the deal pales in comparison to the $200 million paid by AMC Networks to acquire the initial 49.9% stake in the cable network in 2014. Back then of course, the TV landscape and cable veterans like AMC Networks were still riding the final waves of high ratings and high margins from the pay TV business, before the wheels truly came off. Since then, streaming competition has altered the market irreversibly, making cable channels like BBC America inherently less profitable, hence the dramatic fall in valuation. The deal is…