There's a danger in assessing Republican prospects in a state based on recent election results. Democrats have done very well in presidential elections in that time frame, winning four of six, none of which were particularly close. The worst performance for the Democrats during that time frame was John Kerry in 2004, and he still managed over 48% of the popular vote. A state would only have to be slightly Democratic leaning for us to expect it to go Democratic in every election since 1992.
An example I like to use to illustrate this is Wisconsin, because people were hyping Scott Walker's ability to win in a "deep blue" state back when he was being treated as the frontrunner for the Republican nomination. As evidence people point to Wisconsin having voted Democratic in every presidential election starting in 1988. But its Partisan Voting Index is only D+2! Indeed the only elections in which Wisconsin even came close to mattering during that time were 2000 and 2004, and both Gore and Kerry won the state by razor thin margins. Gore won by less than 6000 votes, while Kerry won by just over 11000 votes. Really the most impressive Democratic performance during that time was 1988 itself when Dukakis beat Bush by a decent margin, but that was a long time ago. Long enough ago that West Virginia was one of ten states that went blue.
Another way of looking at it is that back in the late 1980s, states like Illinois, California, and New Jersey were seen as integral to the supposed Republican Electoral College "lock" because they had gone Republican in six straight presidential elections starting in 1968. Then Clinton won them in 1992 and they haven't gone Republican since.
To make a long story short, don't assume states can't go Republican just because they haven't recently. Although I certainly wouldn't expect Trump to be the candidate to flip any of them, it doesn't mean that all those states are safe.