I wouldn't hold my breath waiting for this ("pulling the cable companies into the deal) to happen.
First of all DirecTV has an exclusive rights contract in place for the Sunday Ticket. How would you suggest that be taken away? For starters they would need to be reimbursed - and they vastly outbid what anybody else was willing to pay. Besides, they would surely sue to retain those rights, and the NFL cannot be eager for another lengthy and expensive legal battle - especially one that they can easily avoid.
DirecTV can afford to outbid the competition for the rights to Sunday Ticket because they have a different business model. To them Sunday Ticket is not a profit center, but a loss leader to attract subscribers. Whether it be another network such as espn, or another service provider such as comcast, the number of customers that they have is not going to drastically change by having or not having the Sunday Ticket. To them the ST would be another potential money maker, but at the price DTV pays for it the risk is not worth the potential reward.
Although everyone would love for the ST to be available from their local cable company, that's probably not going to happen any time soon. These type of things are bid out as exclusive rights - otherwise they are far less valuable, and the NFL makes less money because everyone would bid much less for those rights. It's like the Super Bowl, or Sunday night games, or Daytona 500, or whatever - they're all exclusive rights deal, given to one, and only one high bidder. If multiple networks and/or service providers can sell the Sunday Ticket, it becomes much less valuable.
Could the reliability and availability of DirecTV be a topic when the Sunday Ticket comes up for bid again? It didn't last time, so I doubt it will next time either.