Laws do not enforce themselves. They only have power when there are people with authority willing to stand up and enforce them. Without that, they are just words on paper.
Right now all three branches of the Federal government are in the hands of the Republican Party. Trump has one branch; the other two have no interest in opposing him, so long as he lets them do what they want as well. So for the moment, at least, those laws that all three of them disagree with can be assumed to have gone by the boards.
The problem with this line of short term thinking is that it can backfire badly. Yes, they get 1 term or 2, but then the backlash can bury them for decades. Especially in the context of America's changing demographics.
It's not short term thinking at all. This is the GOP's big chance to roll back the modern American system, which was erected by liberals like Roosevelt and Johnson, and replace it with something more to their ideological liking. Doing so has been their #1 political objective since the 1930s.
Why on earth would they fail to seize such an opportunity? Especially when, as you note, changing demographics mean that another one is unlikely to ever come again?
Right now all three branches of the Federal government are in the hands of the Republican Party. Trump has one branch; the other two have no interest in opposing him, so long as he lets them do what they want as well. So for the moment, at least, those laws that all three of them disagree with can be assumed to have gone by the boards.