It’s very simple. Miners on the Bitcoin-network make BTC when the find a valid block. So the BTC goes to the miner’s address. In SAFE people run Vaults. So when someone runs a Vault, let’s say with 20GB of data and 1 of the the chunks is requested he might Farm some Safecoin. So the owner of the Vault gets Safecoin added to it’s address. At the same time the data_managers will pay 5% of that value (95% less than the Farmer) to an address owned by Maidsafe. That way they make 5% of the coins mined, this proces goes on 24/7 day after day. So it could be a steady income stream where Maidsafe get’s coins credited to their address.
So let’s say $20 million worth of Safecoin is Farmed in 2018. That way Maidsafe get’s $1 million worth of coins to be spend on development. So they might offer rewards to external developers or develop stuff themselves. Or a combination of that.