When someone wants to cash in and out of Steem, the projects that make that the easiest will be the ones that separate themselves from the pack. People wish to have one-click buy Steem in their account and one-click cashout into their legacy fiat wallets (banks, PayPal).
This will be the big one. Earning through use of the apps and being able to cash it out directly or having a system to use it from your phone to either buy goods or a at a debit terminal and tap your steem. This will be the selling point when it goes mainstream. Earn STEEM through actifit and use it to buy new sneakers. Earn STEEM though steepshot and use it to buy a new phone. People will sign up when they don't realize they are signing up to the steem blockchain it will be so similar to using any other app. The only difference will be the wallet with their tokens inside.
Exactly. People want instant gratification and running some miles and getting to buy new sneakers with the points you earn instantly, that is what will change the game.