I don't buy this info for a second but let's just say it is accurate and the top brass is considering doing this. That would have to mean they have decided they will be moving on from Garrett and Linehan in the near future and that they no longer see Dak as the future franchise QB. You couldn't make these moves and expect for those three to be key members of the team moving forward for very long.
If the Cowboys have lost all faith in Dak, just let the season play out. If he plays poorly, the Cowboys will have a bad record and be in position to draft a QB high in the 1st round.
If by some miracle Romo comes back, plays well, the Cowboys still won't win the Super Bowl and will just be in a poorer draft position.
Really, Cowboys should be using the rest of this season to determine whether DAK is the long term answer or not. If he's not, move on. Forget Dez, Romo, Witten, etc.