Gardner is too far out of step with the party on immigration for the 2016 election, and Cotton doesn't add anything electorally, so I doubt either of them is on the ticket in 2016. Plus, with both of them as first term senators, I find it exceedingly unlikely. Cotton is young enough that he could easily wait until 2024, which won't be a re-election year for him in the senate, and will likely be an election year with no incumbent to beat.
As is Gardner, who in 2024 would only be 50 years old. By then, the GOP will probably be closer to Gardner's immigration position than what they are today. Plus, Cotton is stiff as a block of wood.
