This is an interesting theory, to be sure, although it flies in the face of what Rian Johnson intended to accomplish with Snoke’s death in The Last Jedi: further developing Kylo Ren’s character.
If Snoke is still alive out there and will be back for Episode IX, that takes away the dramatic beat that his fatal stabbing provided.
In the end, it was overconfidence that was Snoke’s downfall.
Wanting to get Kylo to a place where “he was standing on his own two feet as a complicated villain” as well as not wanting to repeat the Palpatine story from the earlier Star Wars movies, Johnson decided to take Snoke off the board and have Kylo become The First Order’s new Supreme Leader.