The cuts to id Software have hit the teams that develop id Tech hard, without a doubt. But rumors that there's now virtually nobody working on the engine are false. Sources tell me that there remains a solid stack of expertise for id Tech across id Software itself, and Machine Games. I'm told Microsoft also has no plans to shift either studio forcibly to Unreal Engine, which seems to have become the default for Microsoft and many other core game makers.
Microsoft provided us this statement on the topic: "There are dozens of people working on id Tech across multiple locations. Reports that there’s only one person left in Texas are inaccurate."