The Kansas City Chiefs have had one of the youngest offensive lines in each of Andy Reid and John Dorsey's seaosons in Kansas City. That will likely continue into the 2016 season where the Chiefs are projected to have the sixth youngest starting offensive line with an average age of 25.7.
This is based off of this offensive line: LT Eric Fisher, LG Jarrod Pughsley, C Mitch Morse, RG Laurent Duvernay-Tardif, RT Mitch Schwartz. (Thanks to Blogging The Boys for running the numbers. Full list here.)
The questionable ones there are the two guard positions.