There are many martial arts which have faded into obscurity with the rise of new popular martial arts. Some have never caught traction at all. In fact, there are simply too many martial arts to count, but only a handful of them are actually combat tested. Aikido is a Japanese martial art which has been widely popular but have never actually been tested in combat.
Many debate the effectiveness of this martial art, and the poster boy Steven Seagal does not help its reputation. To be effective, martial arts should include full contact sparring or they are just purely theatrics. One can practice a movement as much as they want, but nothing but experience can prepare someone to properly execute a movement in an actual situation.