Sometimes people on this board are concerned about a flight cancellation. They see a particular flight, on a particular day, with many unassigned and presumably unsold seats. So they think that particular flight will be cancelled. That's unlikely to happen.
Also, when people look at seat assignment maps 3 or 4 months before the flight date, they're not taking into account that most people don't book as early as they do.
A scheduled flight with an occasional light load in one direction will operate as scheduled, except under unusual circumstances. For example, if a terrible weather condition somewhere in the country prevents inbound aircraft from arriving at a hub airport, then an airline may reassign aircraft to the flights that make the most sense to operate, based on passenger load. Normally, however, a flight will operate as scheduled, even if the passenger load is lighter than average.
If a given scheduled flight fails to produce a sufficient financial yield consistently — day after day, month after month — then an airline is likely to drop the flight (or even the route) from their schedule.
I wouldn't worry about the passenger load based on a seat map for a flight 3 months from now. Most of my flights to Orlando show as nearly empty 3 months out, but are full on the day of the flight.
A separate issue is that the legacy airlines adjust their schedules far more often than one would think. Delta seems to the worst. Sometimes the change only involves a few minutes or a different aircraft type. But sometimes the change can mean that connections no longer work or that there is no longer service at the time of day that you had been ticketed for.