The next communications supercompany? Dish Network Corp. made a $25.5 billion bid for Sprint Nextel Corp., an unsolicited offer that, if accepted, would combine one of the country’s largest pay-TV providers with the third-largest wireless-communications company. It could be a shrewd move for Dish Network, which is seeing the pay-TV business face increased competition from other distributors as younger consumers opt for services like Netflix and other digital platforms. Absorbing Sprint would allow the company to offer Internet and phone service along with satellite services.