Does Andy Dalton Threaten Dak Prescott's Future in Dallas?

Dak Prescott and the Dallas Cowboys have been negotiating a contract extension for MONTHS. Because of that fact...the Cowboys signing of Andy Dalton has caused speculation to run rampant concerning Dak's future in Dallas.

Why did Jerry Jones sign Andy Dalton? Is it a sign of frustration with Dak Prescott...or is Dalton just an expensive backup quarterback?