In the history of the United States, there have been 29x that an open SCOTUS vacancy has occurred in an election year.
In ALL 29 cases, a nomination was made by the incumbent president regardless of whether the candidate was accepted by the Senate including up until the last day in office.
So for Trump not to nominate a candidate would go against the grain of a 100% historic precedent.
We found AF Branco’s cartoon especially on point.
In November 2013, Senate Democrats led by Harry Reid used what was called the ‘nuclear option‘ to eliminate the 60-vote minimum rule (out of 10 votes) on executive branch nominations and federal judicial appointments except those regarding confirmations to the Supreme Court.
Rule XX allows the Senate to decide any issue by a simple majority vote. i.e. 51 votes.
In April 2017, Senate Republicans under Mitch McConnell merely extended the nuclear option of Reid to Supreme Court nominations as well which prevented the filibuster against the nomination of Neil Gorsuch.