Someone mentioned having the elders, then people with small kids going first and then anyone else - well that could lead to some folks feeling like they don't want to participate either. "I'm good enough to bring stuff for all these folks to eat, but not good enough to even have an equal chance at the premium dishes. " vibe would have many I know running for the hills
The combination would be particularly bad for young, single people - bring enough to feed 5 or 6 people, and wait until the end before you get to eat. By that point, you're paying more for your meal and getting a worse meal than the rest of the people.
Another subtlety - "enough to feed one person" varies widely by person. So someone with a light appetite can bring enough to feed themselves 5 times over, which may not be enough for two young men with voracious appetites.
For singles, there are several ways you can approach it. Bring smaller amounts, and don't worry that everyone in the whole room doesn't get to try it. Bring larger amounts of cheap food - you bring 7 day coleslaw rather than a meat dish. Bring a substantial dish, but not every time, so it averages out.
I figure that if you're holding potlucks and lack of food is a problem, whatever the venue, then the easiest and simplest thing to do is to find something else to do, rather than trying to force reluctant people to bring more or better food.
If you're using potlucks as a form of personal hosting, then take indifferent participation as a sign that maybe your friends and family don't want to be catering your hosting. At a workplace, recognize that maybe your employees/coworkers don't want to be staying up late to cook and lugging food into work on the bus. In a church/organization setting, accept that potlucks don't work with this group, and try some non-food focussed socializing.
For some groups it works fine - like others, I'm used to potlucks with extra food, not running out. But when it doesn't work, it's often a sign that potlucks aren't a good fit with that particular group. Maybe people can't afford it, maybe they're too busy to make an extra meal as admission to a social event, maybe they don't cook, or are terrible at it, maybe they're simply tired after too many years of potlucks, or maybe they like to eat and don't get that they should contribute. In any potluck group there will be people who have trouble contributing - due either to living arrangement (living in a dorm room, say), or finances (unemployed, for example). A healthy potluck absorbs these people, who later contribute when their circumstances change, but if you have too many people like this, or an indifferent potluck in the first place, it can push it over the edge into not working.
I totally agree with the bolded above.
And I'd like to point out that a potluck does not mean everyone has to cook. Someone can bring a few bottles of coke; the plates & utensils; premade rolls from the grocery store, a bag of chips & premade dip, etc. There are a lot of things that one who doesn't want to or is unable to cook can contribute.ETA:
Of course, if too many did that, you'd be in just as bad a situation as too many people not bringing anything.
As a veteran organizer of pot lucks, I think that the organizer should either do a sign up type of thing where people say in advance what they are bringing, either specifically or generally, or do a pre-assignment.
In my case, I always ask people to tell me what they are bringing, and once in a great while I ask people to switch if possible (too many pasta dishes comes to mind as a reason I've asked) and people are pretty ammenable to that.
In a large group (we used to do this for our annual cub scout pack end of year potluck when the kids were little) the MO was to assign dishes by alphabet of last name. Example: A-E salads, F-I desserts, etc. It worked out great. No one actually policed what everyone brought so if you were assigned main dish and brought cookies instead, well, no one checked. But it worked out pretty well as we always got a huge amount of food and a good mix. And this was a situation of people needing to bring a lot as you had whole families in attendance. So, it can be done. It just requires that everyone, or at least the vast majority, bring their fair share.