DeVito will almost certainly miss the remaining two preseason games. The timetable for his return is unknown. There is reason to believe this injury will keep him out of the Jets' regular-season opener against the Buffalo Bills. Said head coach Rex Ryan (via ESPN):
[A calf injury] is never good for a defensive lineman.
This injury most likely means that rookie defensive end Quinton Coples will get to start in the Jets' third preseason game this weekend. Mike DeVito is known around the NFL as a solid starter and is considered one of the better run-stuffers in the league. He has been a mainstay on the Jets' defense since he joined the Jets as an undrafted rookie in 2007.
Fortunately for the Jets, they have significant depth at defensive line this year. However, DeVito is a veteran presence and a reliable starter. If he is forced to miss their Week 1 game against the Buffalo Bills and running back Fred Jackson, his presence will be sorely missed.