Another great post!
Yes, Wall St. is coming. They've dismissed it as a fad, only for criminals and a bubble, but that's exactly what they said about the Internet about 20 years ago - and they've all adopted that now.
You're completely right. The current $600-$700 Billion Market Cap is peanuts compared to where it'll be when the real money arrives. And when it does, as the market grows larger, it will first shoot up, then stabalise. The reason cryptos are so volatile (compared with stock markets) is because they're relatively small. Institutions and investment banks will be the new whales.
At the same time, governments will regulate as much as they can, and make sure they can tax it. That will cause fear and push back, but the cat's out of the bag now, and it won't go back in!
I can see Bitcoin being dwarfed in size and importance by another (possibly not yet launched) coin/blockchain in 2019 too. As the big money does come in, they won't necessarily put it in the same place we have. They'll want more control, and a safe haven for their investments. But Bitcoin will look like an absolute steal at $11k, even $20 when the $Trillions starts to pour in.
2019 is certainly going to be interesting, and some new wealth is being created right now. Exciting times...get in while you can!