Welcome to the Forum! Don’t worry most of us end up becoming a bit obsessed about the hogs!
If those hogs have been visiting you regularly, it seems more likely that they have gone to hibernate than that they’ve found another food source. Hogs tend to visit several gardens anyway, so if they were still out and about would likely still visit yours. Fingers crossed that they have a successful hibernation. Hibernation is always a worrying time, but we just have to hope for the best that they will return safe and well in the Spring.
It’s possible the one still visiting has decided not to hibernate. Not all hogs hibernate and that’s ok, but if so, just keep leaving food out for it. Water is best left available all day every day, anyway, including through the winter. Hogs are known to emerge from hibernation for short periods and may welcome a drink. You may want to leave some dry i.e. cat/kitten biscuits out all winter, even once/if they’ve all hibernated. A hog from elsewhere might turn up at any time so the food would be useful for that even if not for your regular visitors.
Good luck to all the hogs there. I hope they all do well.