Alaska has trended D in every election since the year 2004. Bush won Alaska by 25 points in 2004, while Trump won Alaska by 15 points in 2016. It has been a slow and steady drip drip in Alaska, no dramatic swings, but it adds up over time.
But you also have to compare to the national vote. Bush won by 25 percent in a a 2.5% popular vote win. You can’t expect that margin to stay in 2008 and 2012, which were weaker years for the Republican brand.
2004 - 22% +R
2008 - 20% +R
2012 - 10% + R
2016 - 17% + R
Might seem like there were some big swings (2012), but with these smaller states, percentages can vary widely, without speaking to trends.
Finally - Alaska is a state that is losing people, an event that often favors the Republicans. Since the 1970s, it’s been good for 100,000-200,000 gain per decade. Since 2010, it’s gained only about 30k people, basically stagnating since 2011-2012. It is also a state that is getting older.
If AK melts I don't think any of that will matter, people will just vote for the party who isn't actively detsroying their state
