A massive media merger unveiled Tuesday would put San Antonio TV station KENS5 in new hands and further consolidate Texas broadcast outlets, igniting concerns from media watchdogs about dwindling choices for local news and content. Irving-based Nexstar Inc. plans acquire KENS owner Tegna Inc. in a $6.2 billion deal that will test current federal regulations on media ownership limits. If approved, Nexstar — already the nation’s largest local TV station ownership group — would control 265 stations across 44 states and D.C., covering around 80% of U.S. households. That’s more than double the scope allowed under the Federal Communication Commission’s 39% ownership cap.