[morzh]

They are called trimmer capacitor.

"trimmer" is used toward caps and resistors that are variable but are adjusted once and then stay in this position forever, unlike the true variable caps and resistors that are used for tuning / regulating. There is always need in them so in foreseeable future I don't think they are going to disappear, especially the thrim-pots.

Although there are varicaps (voltage controlled diodes that are used as trimmer/pullable caps) and digitally controlled trimpots which are actually microchips using MOSFETs and EEPROMs.