One of the problems Bergerac has is that it has a population of 30 000, le grand Bergerac is about twice that, in other words it is too small to be particularly dynamic especially since 40 minutes away there is Périgueux. Périgueux is not only the Préfecture so has virtually all the admin for the département but also has far bigger satellite communes meaning there is an incentive to set up businesses there and there are far more schools, collèges,lycées and post-bac possibilities which encourage at least some young people to stay there.
I had a look at a list of English towns with similar populations and came up with Beverly, Deal, St Neots, Sedgeley (I can hear you say "where????") these are all places that actually have LESS going on in them than Bergerac does, but exist as dormitory towns eg Beverly for Hull & York & St Neots for Cambridge - the way things are going Bergerac is going to be a dormitory town for Bordeaux, it already is to an extent, just look at the development along the river from Lalinde to Libourne. But dormitory towns have their own set of problems. At the moment we are rather betwixt and between.
Bergerac is the 2nd town, size-wise, in a poor department - that is just reality, have you ever wondered why the Dordogne is so 'unspoilt' and pretty? Apart from geography, it is because nobody has ever really had any money to spoil it. (Just look at some of the truly hideous buildings put up in the 60s and 70s when they had a bit of money to splash...)
Bergerac actually has quite a lot going for it in theory BUT like many places doesn't have any significant industry apart from wine and even that employs people in the wider area, not really in the town. I don't think an economy founded almost only on services and non-essential retail can do well in times of economic crisis, simply because these are areas people where will cut back on spending. Probably the biggest employers in town are the EN and the hospital, ie the State, funded not voluntarily by people investing but through your taxes and mine...
If I look at Ste Foy La Grande, where I work, I have some data for my pupils' households and over 30% of them are from homes where NEITHER parent has a job. A good third: and these aren't retired people or rentiers, they are people in their late thirties to early fifties, they might like a job but there aren't any. That is a huge proportion: and these are pupils in Lycée who are likely to be in a more fortunate situation than pupils in other forms of post-collège education, or none.
Setting up a bijou business isn't going to work there because only a minority can afford to use it regularly and revenue will be sporadic & fluctuating while overheads will stay the same. What is needed is something that operates year-round like the canning factory or the late SNPE in Bergerac or on the other hand something producing high-value low bulk goods requiring skilled labour, which would bring revenue into the area. A lot of people from here with qualifications go & work in a bigger city because there are more opportunities for them now and they can't afford to wait for an upturn which would get them a job that would allow them to earn a living. Qualified young people who return usually do so to take over a family business eg a Notaire's étude, which is again a fairly niche thing.
Unqualified young people have no incentive to stay either because if you're going to be in a rubbish situation you can be in one more amusingly in Bordeaux or Toulouse, away from your parents, where casual work is easier to come by & so are drugs etc. if they want to set up that type of business.
The majority of my present pupils have never taken an aeroplane, many of them have never been abroad at all or even to Paris - the same goes for their parents, and making the airport itself more attractive, however it is done, isn't going to change that, there are other reasons for their not using it.
So I'm sorry if I seem flippant or insensitive about airport improvements but they do seem a bit of a first-world problem to me as a French person living here (rather than a foreign incomer): tourism is an important albeit seasonal source of revenue for a lot of people both local and expats but by no means for everyone, nor is it the primary source of revenue for many who use it to put a bit of butter in their spinach (and most of their clients don't use the airport, they come by car):
it isn't surprising that we see things diffently but good grief, sometimes we really don't seem to be living in the same world at all.