While I believe Dak will be the Cowboy's QB for 2020 and beyond, the real question is not whether there are better options available, but whether the team can achieve or exceed expectations with another QB. In essence, this is a classic option theory application.
I could argue that the much misused "bus driver" QB could achieve comparable results as Dak when you consider that the money saved in signing Dak could be used to bolster other positions. I am not advocating the team take this approach. However, I do believe it extremely shortsighted if the FO doesn't have legitimate fallback plans in the event Dak doesn't sign.