The thoughts of Snoke being Plagueis have been pretty much ruled out. A 2 am rumination coupled with insomnia brought about the following thought and it just won't go away. I'm sure it might be coincidental that the giant Death Star 3.0 was named Starkiller base, but it rang a bell in the back of my Star Wars infused brain. What are the chances that Snoke is Galen Marek (or one of his clones)... I know Disney axed a bunch of stuff and turned it "legend" and made a bunch of things non-canon, but it is an interesting thought. Whether or not it is true, I don't know (nor do I care because it's fun to speculate), but if you think about it, it could make sense. Galen Marek aka Starkiller was Vader's secret apprentice. Long story short, there were betrayals and backstabbings and all that. Kylo Ren's obsession with Vader would make for a very interesting twist if he was being trained by Vader's old cast-off apprentice/clone of his apprentice.
Like I said, it is an interesting and fun thought/theory and is a play on the Starkiller base and the code name for Vader's secret apprentice. Thought the way Star Wars was sort of "Disney-ified" I wouldn't put it past them. After all, they said all of the EU was no longer canon, yet we saw 1/2 of the Jacen/Jaina story with the story obviously tweaked a bit.