Even if Trump appoints the next 2 or 3 Supreme Court justices, he might first fill the vacancies of a couple of the older ultra conservatives. Clarence Thomas, John Roberts and Samuel Alito. John Roberts seems to support gay rights in a more traditional way, and he might uphold gay marriage as precedent now. I also just read on Axios he is considered the most moderate of the conservatives on the court now. Sam Alito the same article says, is the most conservative. As I already said, people like Antonin Scalia (who retired in 2016) have evolved their views a little since they joined the court. Neil Gorsuch seems to support gay rights in a more traditional way. Job discrimination, equal protection under the 14th Amendment, etc. As I also said, he might uphold gay marriage as precedent too. Gorsuch was appointed by Trump in 2017. Trump might appoint someone like him again. So this still might get interesting.
To paraphrase Churchill's famous quote: Any Supreme Court Justice who holds the same opinions at 60 that he/she did at 30 is a Supreme Court Justice who has wasted 30 years of their life.
Thanks to McConnell's Machiavellian obstructionism, Republicans long ago gave up on trying to pass their deeply unpopular policies nobody wanted via the legislative process, and have instead opted to impose them by force of law through a thoroughly stacked kangaroo court system. More than a quarter of federal judges are now Trump appointees. Trump appointed three of the nine sitting Supreme Court justices, 30% of the nation’s appeals court judges and 27% of district court judges. He nominated them to advance his neo-Fascist agenda (all his judicial nominations were vetted by the Heritage Foundation not for competency, but ideological purity), and because they're relatively young. Currently the Federal judiciary has 41 vacancies, with 13 pending Biden nominees without a snowball's chance in hell of getting confirmed. The American Bar Association has rated more of Trump’s appointees as “Not Qualified” than any other president in modern history (so Republicans stopped using the ABA's imprimatur during the confirmation process). Worst of all, the average age of Trump’s judicial nominations was about 48.5 at the time they were appointed, and Federal judges serve for life. They will be collectively shitting and pissing in democracy's well for decades, long after you, I, and Trump are dead and gone. We're irredeemably fucked...and I don't give a bubbly fart what idiotic rationales and lame excuses you might have; if you voted Republican, pissed away your vote on some zero-chance-of-winning 3rd Party, or couldn't be bothered to vote at all...YOU'RE THE ONE WHO FUCKED US! YOU PERSONALLY! AND I WILL NEVER STOP HOLDING YOU PERSONALLY RESPONSIBLE!