It depends on whether the US Senate flips to the Democrats or not. 6 months ago, the Senate flipping seemed impossible. But now, the Senate is indeed in play.
If the Democrats take the Senate (the House of Representatives seems like a given), then the Democrats will have the upper edge (since the Senate must approve all nominees to the Supreme Court as per the US constitution.)
In 2016, Obama nominated Merrick Garland to the Supreme Court, however, since the Republicans controlled the Senate they told Obama to go fuck himself and refused to even consider Garland as a Supreme Court Justice, though by all accounts, he was quite qualified. This went on for a year.
If (and it's a big if) the Democrats retake the Senate in November, they will now return the favour, albeit for 2 years. There simply will not be enough time between now and the November elections for Trump to nominate another candidate for the Supreme Court. He has to wait until after the November mid terms. The Republicans know this and this is why they are going batshit crazy to get Judge Friendly Disposition into the Supreme Court so that they can stack the deck in their favour with respect to legislation for the foreseeable future.
It doesn't even have to be a Senate flip. The margin of control of the Senate is now 1 vote. And that vote just died of cancer and hasn't been replaced. (Or has he?)
The GOP is foolishly incompetent and out of control. This is the party that promised to replace Obama-care for 8 years and then couldn't get it together when it had the chance because of indiscipline and disorganization and weak leadership. All you need is for 1 or 2 GOP senators to balk at voting for a rightie judge and the whole thing goes down the toilet in a flood of shit and tears.