2D Shmups - History, Prospects?

Thanks to Gamers.com for their article discussing a brief survey of the 2D shoot-em-up (shmup) market. The article summarizes: "Shooters seem to have a very basic appeal, rewarding as they usually do indiscriminate destruction. They're also a pure example of the most basic of videogame challenges - simple, instantaneous, twitchy response... there are still a few gamers who seek classic shooting action, and a few companies willing to support them." It goes on to reference classic Japanese shmup companies such as Irem, Treasure, and Cave, and provide information on their former and current projects.