2016 and 2020 are locks for Hillary. By 2024, AZ, TX and GA at least will all be solidly Democratic, making it impossible for a Republican to win the White House.
I'm thinking they should cut their losses and redirect all resources to trying to hold the UT legislature. Even that will be tough, because that state is rapidly trending D.
You're neglecting the solid pro-Republican trend that happened in 2012. While it wasn't enough to let the GOP win in 2012, by 2024, extrapolating from the 2008 -> 2012 swing, one gets the following 2024 map, with Utah as the GOP's best state at 102% of the vote.