I would say that DTube is likely to do really well because the timing is perfect. Not only is it a nice addition as another content format for Steemit, but its development has come hand in hand with YouTube/Google making life so hard for content creators that many are actively casting about for new places to publish. So it fills a niche.
DTube also has a great opportunity to become "The People's Video Channel" because it is probably more attractive to the smaller publisher, rather than those who are already publishing to a few million viewers. Which seems in keeping with the underlying ideal of Steemit to make people's lives better.
Bright Blessings to you @surfermarly!
To be honest, I don't think that a youtuber really cares about the number of followers. They only care because that's the number they're able to monetize: views. On Dtube that's not relevant, one single whale vote can change your daily income considerably. So what they care about is the number of $$ in their bank account at the end of the month :-) On DTube they may be able to make more money in a shorter period of time. I'm not talking about the top 10 most successful youtubers that have established contracts with advertisement partners and earn millions of dollars per month. These wouldn't become too happy on DTube right now.
Still the smart ones open their accounts as soon as possible in order to start growing their brands in the fast growing early adopters' market.