Charter Communications has offered up a masterclass in marketing the double play broadband-pay TV bundle over the past 12 months to slow the flow of cord cutters, leaving rival US operators scratching their heads. This is more of a temporary cushion than a long-term solution, however, which is why Charter is looking at letting its Worldbox set top take flight – as it prepares to target the hybrid device at broadband-only subscribers. In the same breath, Comcast is building on its decision last year to post free Flex devices to broadband subscribers, whether they asked for one or not, by unleashing the streaming hardware outside of the cableco’s footprint available over any broadband connection. The two parallel moves from Comcast…