The NFL does not invade the Saturday schedule, that's for college football. At this time, however, there are talks that the college football season could be postponed or cancelled altogether. Should this happen, the NFL is exploring the idea of playing a few games on Saturday.
From PFT-
The idea is that most games would still be played on Sundays, but a few games could move to Saturday. The Monday and Thursday night schedule would not be affected. This would happen only if there is no college football at all on Saturdays.
The NCAA has made no decisions about whether the college football season will start on time, but there’s some sentiment that college football can only begin if it’s safe to open college campuses to tens of thousands of students. The NFL may be able to start before college football, especially if games are played in empty stadiums.
Of course, the NFL also has the possibility of postponing or cancelling games themselves but as of now, they are on schedule to start the season.
Andrew Marchand of the NY Post details the benefits of the NFL playing on Saturday.
But the Saturday plan makes a lot of sense as it would create an open TV window for the NFL. The NFL already schedules Saturday games after the college regular season concludes in December.
The NFL could go to more extremes if Saturday is freed up for its whole season. It could have a triple-header with games at 1 p.m., 4:30 and 8, or just have one Saturday game of the week.