Dances with Gnolls
It is an interesting thought, but Luke had shut himself off from the Force according to the movie. Wouldn't that tip the scales to the Dark then? Or is a Force user who shuts themselves off from the force still able to effect any balance there?The way that the sequel trilogy takes it, I think is that the idea is that there is balance between force users.
Annakin, in that way, really did finally bring balance to the force, as long as you don't look at all the extraneous material found in anything but the movies themselves.
When he did the Jedi Purge and it was Him and the Emperor on the Dark Side and Yoda and Obi-Wan on the light side. When Luke first comes to knowledge of the Force, Obi-Wan dies.
For that while, the Force is balanced between light and dark in the new ST way of seeing things.
It is explained in TLJ thus, that when one side rises, the other raises someone else to match it. Thus, the idea probably is that Snoke came into being because Luke was there, and since the Force had finally been balanced, Luke being Lightside needed a Dark Side user to balance it out. Thus, Kylo's balance would be Rey.
The idea Luke expressed in TLJ would be then, that as long as there are those on the one side of the Force, now that it is balanced, there will always be those on the other side. His idea is that if the Jedi were to end, so would the Dark side force users.
That probably doesn't work really with what Lucas envisioned or his other material (as seen in the Clone wars and definitely what is seen in Rebels, but works with the movie continuity and seems to be what Snoke explains in TLJ). Lucas (who has changed his mind several times as he said one thing in the past and then something different later on in various interviews) seems to have originally based the Force off a similar idea as Buddhism's relationship with Zen. It is the idea of balance within the individual, with unbalance being excessively giving into emotion or one side of cravings or other things. Thus, the idea that the force itself is balanced, but the Dark side is an unbalanced force. To balance it would be to do away with the Dark side (as Vader eventually did).
BUT, under Disney I think their interpretation is more akin to the idea of balance being between the light and the dark. Each needing the other in order to exist. It's more of a Yin/Yang than a middle road type idea. Thus, if only one side has a Force user, then the force will make another arise on the other side now that it is balanced.
I think that's how TLJ explains it and that's sort of the explanation also of how Snoke actually exists now.