The most innings pitched by a pitcher in a single game is 26 innings will that record ever be broken?

No. The way baseball has become is they try to protect the pitchers arm. They care a lot about pitch counts and often wont let players get too far north of 100 pitches depending on who it is. Lets just say that the average batter takes 4 pitches to get out and that the team averages 1 baserunner per inning (those are pretty average). 26 innings x 4 batters per inning = 104 batters faced in 26 innings. 104 batters x 4 pitches = 416 pitches. No starter will ever come close to that