It will be very hard to get *everyone* using Bitcoin. I will be happy, if a simple majority of the world population approves the usage of Bitcoin. But we have a long way to go before we reach that level. Right now the user base is around 100 million, and that needs to be increased by 40x or 50x before we can claim world-wide acceptability. And as you said, scalability is a concern, but hopefully a few hard forks can resolve it.