It is way more than likely the next game NRS will be working on is Injustice 2. Alternating titles gives them the chance to work out mechanical/technical kinks without isolating either fanbase too much if something doesn't go over well. So I wouldn't hold my breath for another MK games within the next three years if I were you.

But a White Lotus spinoff game does sounds fantastic; I would just prefer it comes after they wrap up the main storyline in some way, otherwise it could come off as disjointed and awkwardly placed within the franchise.