"When 930 years old you reach, be as good you will not."
He has lived his very long life as a small being. He grew up green, with big ears. Though he didn't make a big deal of it that we know of, there is a hint that he was self conscious of his tiny stature:
"Judge me by my size, do you?"
"Size matters not."
It sounds to me like he was trying to convince himself.
The last time we see Yoda, he is lying in bed, dying. But is he dying? He just disappears. I didn't see a body. Oh sure, he shows up later as a force ghost. That just proves that he isn't completely gone. He has become another kind of being. Transparent, but visible to Luke.
Fast forward about 30 years. A new leader has risen. He is holographic and huge. (Remember, Yoda was holographic and tiny last we saw him.) He is transparent at times, and visible to Luke's nephew. Snoke is just as bald as Yoda, but he does not look as good. Clearly, he has aged in that time. His study of the Force has clearly taught him to overcome his tiny size and long poiny ears. He is now HUGE! Even seated, he towers over his underlings. Perhaps it's the memory of Darth Vader that turned him bad and made him talk forward. Or maybe it's the influence of General Hux (who looks suspiciously like Bill Weasley ... coincidence? I think not.) and/or Kylo Ren. Snoke seems to be just as respected by the First Order as Yoda was by the Jedi.
Yep. Supreme Leader Snoke is clearly Yoda.