The airline industry has taken advantage of customers for decades. With security regulations and high fuel costs cutting into profits, airlines are trying to find new ways to make money. They are charging new fees, such as for checking bags. They are also packing more people into fewer planes. The airline industry is running into trouble because of the way it treats its customers.
I'm going to say the general idea of "customer service" is falling by the wayside. With customer service call centers relocating to countries where labor is cheaper (and English is not the native language) many companies are choosing a cheaper product over quality.
A recent book Your Call is (not) That Important to Us is just one of several compilations of accounts of customer service gone very very wrong. I think this kind of negative marketing is what the customer service sector needs more of in order to change. That and the companies who have maintained quality customer service could probably advertising that even more - as it is becoming more and more rare - but remains important to most people.
A high-profile sector that is in trouble in the United States is newspapers. They are losing ad revenue and (to some extent) subscribers to the internet. They have not yet found a way to get people to pay for news content on the internet and this is costing them.
I am sure there must be many new goods and services for which market potential has not been fully utilized. This includes products for which existence of great market potential is well understood but is not fully realized in practice. As a matter of fact most of the new innovative products using latest technology will come under this category.For example, electronic good of various types incorporating latest technology and features. The list of such products will run into thousand. However, one product that has caught the attention of many big manufacturers across the world, but is not really being sold in very large numbers is a small care comparable to the Nano introduced by Tata Motors. After Tata Motors showcased this car in various international auto exhibition, some of the biggest auto manufacturers across the world have initiated action to launch similar cars in the market.
In addition to the goods and services with well recognized under utilized market potential, there are sure to be thousands of products for which the existence of market potential is not even recognized by any company or entrepreneur. Therefore it is impossible to name such products.