Figured I'd make a post on the status for 3.9, as we're getting pretty close at this point to RC'ing it and getting a release out there!
Quite a bit of work's gone into 3.9 so far - Linear texture color, proper Deferred lighting and then DirectX 11 support, shorting up lots of parts of OpenGL and work to stabilize Linux, among a lot of other minor improvements and fixes!
The tentative lock-in date to start testing the RC is the end of the month, with a few features to add in yet, such as fixing Linux's lack of file dialogs, and getting my Entity/Component work added into the engine behind a experimental flag(so people who are curious can begin playing with it, while not distrupting any existing work with the standard game classes) as well as a thourough run-through of any other bugs and improvements we can cram into it.
So what's next after 3.9 is out?
Excellent question, Bold-Text-Reader-Stand-in!
From there, we begin to push towards 4.0. Yes, I know, these are version numbers, not decimals, and we could just as easily have 3.10 if we wanted

The break in backwards compatibility in some areas - the art pipeline most specifically - means that it's a sort of line in the sand of 'If you don't really want to deal with porting these big changes, then 3.9 is safe, but after this there may be some large shifts'.
An example of this is the overhaul of the base template I've been working towards to make it less hardcoded and easier to drop in content and packs. Another would be Dropping DirectX9 support. Yep, that's going the way of the dinosaur. It's important, because that frees up a LOT of options that DX11 and modern OpenGL provide, as well as being able to restructure some DX9-oriented parts of GFX to make it less....well, DX9-oriented. This would make it MUCH easier to begin looking towards DX12 and Vulkan, as well.
Another huge one would be switching over to PBR-based rendering. This is another pretty hefty change to the art pipeline, because it impacts materials and rendering in quite a significant way.
So all in all, 4.0 should end up being a pretty huge jump forward for T3D. It'll be bumpy for existing projects if they wanna jump up with it, but I'm fully invested to documenting and making whatever wiki pages or the like needed to make it as smooth a transition as possible.
Just wanted to throw down some info-bits as we move in on the kill for 3.9, and give some light detailings for what to expect for 4.0. If you've got any particular inquiries, feel free to toss them in here

Peace out,
-Jeff