Simply put, there are too many if, ands or buts in the Romo/Cowboys scenario to make assumptions about the possibilities between those two. The FO hasn't been totally forthcoming with the medical details concerning Romo's health, with specific reference to his back issues. Without question, it's somwhat understandable if the team feels it's unwise to make the opposition aware of his specific spinal difficulties, although it's not exactly a secret at this point that his back isn't likely to be invulnerable to further injury.
In addition to Romo's back issues being an unknown to us at this time, it's also unknown whether or not he would be amenable to taking a serious pay cut, simply to remain on the team. Another unknown is whether or not he'd be agreeable to stick around as a backup. Most QBs who have served as a starter for so many years would never find it acceptable.
Yet another indefinite solution to the problem might come when we know exactly what a prospective partner in a trade scenario might be willing to offer for Romo's services. It most likely wouldn't be enough to make up for the cap hit that the Cowboys would suffer.
The facts are sure to become revealed in time but for the present, the unknowns are simply too numerous and vague to lend themselves to making future plans regarding Tony's career a predictable venture. Expect it to take a good while yet before all of this becomes clear.