Yes, Lua is an excellent language and used very heavily in the games industry - a LOT of AAA games use Lua for scripting. I don't see it dying out in the foreseeable future.
Furthermore, on platforms where it is supported, LuaJIT provides a blazing fast implementation (and includes a very very simple to use FFI to make embedding in C even easier) which has shown to be competitive with C in some benchmarks.
Lua is pretty well established in the gaming world as a lightweight but fast scripting engine. It seems to be gaining some momentum in other domains lately too. It's somewhat similar to Python but without the extensive standard library.
It's not going away but it's hard to say how much bigger it will grow. It seems like a good fit for mobile devices. It's used in Corona, for example.
I've dabbled in it. It's neat. In many ways a lot like Javascript but without some of the design errors (I'm sure some will argue that Lua has its own design errors).
I've been using it the last few weeks and I think its a bloody brilliant approach to game development. I can't recommend it highly enough for those wanting to build a cross-platform (Android/iOS/Chrome) 2D game .. its already being used to make big pro games (see Crimson Tides for example) and I see it having a big future as it takes on more and more features..