It as well as the RB adapter had been promised since the very beginning, but even the RB adapter has only just been announced. It almost looks to me as though the team is slowly working through all the adapters and accessories one by one. I would imagine that the LF adapter would be quite similar to the RB adapter. I certainly hope that they produce one soon.
I also hope that they don't waste time and make the very first 4x5 adapter include a multistitch shifting mechanism as well, don't you think?