The court is currently divided 6-3 in favour of "conservatives." Donald Trump nominated three justices to the court, all of them in their 50s.
Going by historical data, the next appointment will probably be made by whoever is President post 2028. This could be to replace Conservative Judge, Clarence Thomas, who is now the oldest member of the court at 73. The trend is for Justices to serve into their 80s.
If "liberals" want to influence the court, then they will probably need to hold the Presidency from 2028 to 2036.
Otherwise the combination of the age profile of the Justices and the electoral cycle would appear to indicate that the current "conservative" makeup of the court will continue for at least the next thirty years.