I think the reason for a Satoshis symbol gaining more adoption first is because of the amount of shitcoins that are worth just a couple Satoshis. When talking about those, it is rather annoying to type of Satoshis every time.
Do you really talk about shitcoins that much that you actually need a satoshi symbol to make it ever so slightly easier? 
Well, actually, I might be wrong since I'm sure many of the time they just say "sats". Though, it would just be neat to have I guess.
We're going to have it once we need it I guess. Currently, a sat is merely worth around $0.0001. We're far away from needing a symbol for it.