Here is some napkin math for the whole masternode/staker thingy.

Stakers that are currently being sold would pay 15% APY (or 17.5% if you have a certain number of atoms), can be "electrified" to 30-35% respectively. I think the XPY converted ones were supposed to pay 25% (50% if electrified) although I can't now find any solid info on that. So let's take 50% APY as the maximum that ionomy could ever need to pay on the deposits in the first year.

The whole ION network will stake more than 100% in the first year (a bit less if the chain does not breath for extended periods of time). 50% of this goes to masternodes, 50% to regular wallets, which means that the "team" does not need any masternodes at all to fulfill their obligations for depositors. They can stake at the regular rate of 11.50 ION per block and still get enough coins even in the worst case scenario (i.e. every staker is electrified, every other wallet on the network also stakes and competes with them, etc).