There's a school of thought in anthropology that the form and vocabulary of the language you speak deeply affects how you think, even to the point of limiting if you can think about certain things. This is called the Sapir-Whorf Hypothesis. There's definitely something to it, although probably not in its strongest "thought on certain subjects is downright impossible" form. It's relevance to software development and our artificial, highly constrained languages, ought to be obvious.
I believe a fairly strong version of Sapir-Whorf when it comes to programming languages. Different languages and programming paradigms lead to different results -- the cost of a software project is directly tied to the conciseness and maintainability of its expression. Even more, software projects grow from seeds, and the structures expressed in the earliest days profoundly affect the form of a system over its growth. So the designs and approaches used in the earliest days of a project can have ramifications for years afterward.
Meanwhile, the actual popularity of programming languages is an absolute mystery. What programming language are you going to be using in 10 years? No one knows. No one. Not Anders, not Matz, not Paul Graham. Twenty years ago (oh lord...), I started working for the magazines Computer Language and AI Expert. I've been hearing about the inevitability of this language or that paradigm or this other environment for two decades. And I don't have a horse in the race; I'm not a language designer, I don't teach anymore, I'm not beholden to a product line.
I do have one theory about language popularity: I think teachability matters a lot. I also have a theory about teachability: You are blind to the teachability of your own paradigm. This is an unfortunate combination of theories.
So that's why Lang.NET is my favorite conference of the year.