COIN will solve three major problems that are stopping most people from investing:
1. It's hard to buy bitcoins. You have to find an exchange, open an account, go through the verification nightmare, get money there, and then (depending on the exchange) buy a little bit at a time until the exchange decides to trust you. It's 100 times harder than going online and buying any stock or mutual fund in your existing brokerage account.
2. It's hard to store bitcoins. You either have to trust it with an online exchange, which everyone says is unwise, or you practically need a computer science degree to figure out how to keep it some kind of cold storage. The average Joe would be unwise to try this at home.
3. It's extremely hard to invest retirement funds in it, which is the only investment funds many people have. (You can do it by setting up an IRA LLC, but that's expensive in terms of money, effort, and time. See
https://bitcointalksearch.org/topic/how-and-why-to-hold-bitcoins-in-your-roth-ira-yes-you-can-do-it-today-396783 for details.)
Once COIN is approved, the average Joe can login to his retirement account and buy bitcoins with practically no effort.
I don't think that the approval of COIN will necessarily immediately launch Bitcoin to the moon, but it will make it much more likely to happen once some triggering event gets the ball rolling.
Of course, it's possible that the price will rise dramatically after the SEC announces that COIN is approved, but before anyone has a chance to actually buy it. It might be worth setting up the IRA LLC and investing Roth IRA funds in bitcoins, where they can grow tax free, before that happens!