La Nouba closed at Disney Springs on December 31, 2017, and Walt Disney World has been without a Cirque du Soleil show ever since. It was announced before the closing that a new show would eventually come to Disney Springs, and that it would be more Disney based. That was all that we knew. No time frame was given.
I happened to stumble upon an interesting casting call. This is taken directly from Cirque du Soleil Casting:
We are looking for a female actress to play the lead character of a 12-year-old girl in our new permanent show in Orlando.
Note that both child and adult candidates will be considered.
That got me curious, so I clicked the link provided and found this under the list of requirements:
Be available starting September 2019 for a minimum of two years.
So it looks like we should expect a new Cirque du Soleil show by the end of next year. Given that September 2019 could be when they start rehearsals, I would say it could be late fall. Remember that this is all speculation on my part, nothing has officially been announced except for a casting call. Still, given all the changes that are coming to Walt Disney World by this time next year, a new Cirque du Soleil show would fit right in.