Right now, this is the ideological position of the SCOTUS judges:
(In the above graph, John Roberts is given a score of +0.20, making him a centrist to moderate conservative. But recent rulings indicate that he has taken a leftist to far-leftist position).
Out of the 9 judges, we have 4 who are far-left (Ginsburg, Sotomayor, Kagan and Breyer) and 4 who are right-wing (Alito, Gorsuch, Kavanaugh and Thomas). The remaining judge (John Roberts) who forms the swing vote, can also be considered as left-wing.
In short, the SCOTUS is having a left-wing majority now.
Now Trump is left with almost 1.5 years, and the Republicans enjoy a comfortable majority in the senate (even without the RINO Murkowski). If there is another vacancy during his term, then Trump should be able to fill it and flip the SCOTUS from left-wing majority to right-wing majority.
And indications are that, there will be at least one vacancy this year... and it is going to be none other than Darth Vader Ginsburg.
Ginsburg is suffering from lung cancer (a type of cancer which has low levels of survival, especially for 86-year olds). As per my calculations, she has 6 months, or at the most 12 months left.
Trump has given indications that he may chose Amy Coney Barrett to replace Ginsburg. Barrett is one of the most conservative judges available and her selection would ensure a conservative majority at least for the next two decades.