They're developing another game with the engine used for MGSV, but you could account that to just trying to recoup costs involved in making that engine. Otherwise I don't know of other console or pc game projects of theirs.
As far as I know there's another MGS spin off they are working on and they continue developing and releasing their annual Pro Evolution Soccer. With the latter my guess is they want a piece of the money-making pie that is Ultimate Team and works so well for EA Sports' FIFA series.