Many (five?) years later, from what I gather, LT has the eye-candy - the rest is perpetually "under construction". It would be hard for it to be anything else, though, as the main developers jumped ship a few years back to work on Eve (which, as a karmic retribution for all my crushed hopes for LT, also tanked and died recently).
Emacs may be less pretty than newer editors, and lots of its APIs are decades old at this point, but it's still the only self-documenting, easily discoverable and extensible editor this side of Pharo and Squeak, which can be used in practice (due to a giant amount of plugins which bring it up to modern standards) for almost any task.
TLDR: LightTable as a powerful editor for programmers is dead - it may be still possible to revive it, but its scope would have to be massively scaled down. It's not going to compete with Emacs & co. anymore, which is a shame, because when it started it had the potential for this.
The core GNU Emacs is quite a bit less lines of Emacs Lisp.
Do you have any idea how many lines of elisp/c the core is? And how gnarly it is? I've read some stories.
IIRC Emacs' C code numbers ~300kloc and includes both bindings to low-level, systems and GUI functionality, some parts of standard Elisp library (writen in C for performance), as well as Elisp virtual machine, byte-compiler and so on. No JIT yet, but at least there's threading support (take that JS :P).
Starting from scratch has many advantages, but it doesn't really work with programs and systems large or complex enough. Otherwise we'd be using a fresh OS every five years instead of working on one of the 5-6 OSes which were all created 30+ years ago.