According to someone apparently at Gallary Nucleus , they were able to get a bit of time aside with Mike and Bryan and were able to ask a few questions.
This interview explains that no, there is not a lost episode that "Remembrences" would have been, since the budget was cut early enough that they planned the season around 12 episodes. It also states that no plans for Korra comics are in motion yet, but that seeing Korra comics (covering topics such as the Red Lotus or Korrasami) are not impossible.
In addition, a lot of the Korra crew is working on something new, jokingly titled "Korra 2.0" (although it has no connection to the original series), and the staff on board does not include Mike or Bryan. Both of them have appeared to have started working on their own, separate individual projects elsewhere.