The GOP will always keep the filibuster in place whenever they control the Senate. Thats because for them, the filibuster isnt there to protect the minority party. Its there to protect THEM when theyre in the MAJORITY. It gives them an excuse not to get bills passed against the wishes of their big-money donors when they hold 51-59 seats in the Senate.
If the GOP ever held 75 seats in the Senate, theyd impose a Senate rule requiring 80 votes to end a filibuster. You can bank on that.