My understanding of an HD redo of TNG has generally been "Don't hold your breath." Mainly because so much of TNG was done on video, meaning that for most, if not all, of those 178 episodes, they wouldn't just be redoing effects sequences, they'd be reassembling whole episodes from the ground up. Thankfully, they saved all that footage, but the time factor would be a major bitch.
You must have missed the recent news from Netflix that starting in July they are going to start streaming all Star Trek episodes, including TOS and ENT in HD, and starting this fall they are going to be premiering TNG in HD, implying than TNG-R is, and has been for sometime, in the works.