I actually dont think that this will happen, at least not in this dimension. Therefore are in the ET community too many wannabe coders out there and to produce a Total Conversion on his own, or with two or three heads will eat a lot of time. We are talking at least about 2 years, but almost more than 2 years. 3 or 4 years are more realistic.
At the moment the situation looks like that:
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ET Src is gpl’ed under version 3
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Since one year is a possible sucessor of ET in development, called Axis Revenge.
A total conversion of the Xreal Engine which is based upon ioQuake3.
The difference between Xreal and ioQuake3 is a overwhelmed tool chain to make maps and at most the graphic renderer which has been replaced, ok there are some other enhancements also made by Tr3b but the mentioned changes are also the biggest.
By the way, the Axis Revenge project is thinking about to switch to the Overdose Engine. Have a look at youtube for it and i swear you will get wet panties 
- The maintainers of ioQuake3 just announced after the release of the ET Source to start the ioWolfET project. What are the aims of the ioWolfET project? See here:
The project was started shortly after the source code release with the goal of creating a bug-free, enhanced open source Quake 3 source code distribution upon which new games and projects can be based. In addition, the project aims to provide an improved environment in which Quake III: Arena, the Team Arena expansion pack and all the popular mods can be played.[13][14][15][16] Notable features added by the project include builtin VoIP support, Anaglyph stereo rendering (for viewing with 3D glasses), and numerous security fixes. A full list of features is available on the project’s website.
Taken from wikipedia.
So we will see a bug-free and enhanced vanilla et, without graphical enhancements so you can kinda say that you get a pimped vanilla-et without the benefits of Xreal. It’s even possible that such old abandoned mods like jaymod will run with ioWolfET, but without Punkbuster.
The maintainers do also know their job, their ioQuake3 project got forked by many other projects like Urban Terror or Tremolous. So they are defnitely able to build and maintain a solid base of the original Wolfenstein Enemy Territory source code.
All other changes will be up to the ET-Community. ioWolfET wont do any game changes. It will just fix bugs and enhance some things like the audio output. ioQuake3 supports 5.1 and 7.1 soundsystems including .ogg support. So you all will finally get high quality sounds out of ET and small soundpacks if you join a public server.
If someone wants to start a new ET’ish project with the Xreal Renderer the persons should know that they go in competition with the Axis Revenge project since they are planning the same thing.
If someone wants a eye-candy engine and new weapons etc should ask the project leaders of Axis Revenge if they could need help, afaik they have lack of coders and mappers.
Imho I would like to see an graphically pimped version of ET with maybe just 2-3 gameplay changes (weapons can stay the same, except a new weapon called venom :oppressor:), without any sort of story behind it. The original ET is as it is almost superb in gameplay, i just would like to see such things like a bomber flying over the map when a field ops is throwing his air-can on the field and before he will be able to call in artillery he needs to deploy his artillery somewhere on the map. On this way will also get Covert Ops and Engineers a new role in the game. Covert ops needs to destroy the artillery and engineers can repair the artillery. The same thing as in ETQW except any sort of drive, or flyable vehicles + the benefit of less field op arty spam and more stratetic thinking.
Probably its smarter to create then a mod with the mentioned changes for Axis Revenge.
I guess in the next weeks and probably at lasts the next 6 months we will see how far the evolve of the original ET source code will go and which projects will remain after some died.