The competition that existed in the postcard market for decades has declined because of cellphones, digital cameras and email. Because there is less of a demand there is far less competition meaning that your chances of entering the market are greater than ever if you can shoot quality images.
There are so many people still going on holiday and the sheer numbers mean that there are still large percentages of people writing postcards. One of the major reasons that they continue to sell is that they are good quality and of a standard that amateurs can