RE: Control line losing popularity? So what!
Control line is a good facet of the overall modelling hobby. I started in UC in 1949 with an Aeromite. Flew til about 1965 then went on to RC only to return a couple of years ago. Not done much since due to medical problems.
Both PAMPA (CL precision Aerobatics) and AMA have experienced decreasing membership. The reason - not really known but RC park fliers and the like may be a factor.
Enjoy the part of the hobby you like - there are no right answers!
Paul