I think creating markets where people transact in Steem and SBD is the single biggest driver of Steem prices moving up. That and getting many more active users on Steemit.com. 

But, like you mentioned... allowing for users to go directly from Steem or SBD  to fiat currency will only increase people's confidence in the currency and will encourage them to use it more often as well. 

I like both ideas for Steem's growth :)