I found this article by NEMA on the market penetration of fluorescent lamps and their sales over the last few years. The picture painted is certainly a grim outlook. It’s definitely worse now, considering that almost 4 years have passed since it was written. Sooner or later, the decline should start to level off as people finish retrofitting things and most lamp sales become for replacement purposes as opposed to new installations.
https://www.nema.org/news/Pages/Linear-Fluorescent-Lamp-Indexes-Continue-to-Decline-in-the-Third-Quarter-of-2016.aspx