Obviously the fees of the fiat on/off ramps will be a bit counter intuitive to the feeless nature, but it's an entry point for users who are then introduced into Nano that then go "Oh so if I have my own Nano I save on fees?".
This doesn't necessarily need to be true, a well designed system can save users money in the short-term.
In terms of a fiat gateway, we could probably see 4-5% fees for card if one of the bigger fiat exchanges implement Nano and perhaps 7-10% if a new Nano fiat gateway launches (crypto services especially new businesses are treated by the few card processors that allow them as very-high-risk so a new service could achieve 10% vs. the 15-20% fees of present but could not expect to get down to the 5% level).
But in terms of fees for SEPA/Wire-transfer, the fee being charged should not be any more than 1%.
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Then for merchants, when compared with the fees they'll pay for accepting card payments, they'd see an immediate increase in revenue for accepting Nano.
We can expect a merchant processor for Nano to charge ~1% fees to merchants to auto-convert payments to Fiat. This is what Bitpay charges for Bitcoin so it shouldn't be any higher.
Most merchants will pay card fees of 1.5 - 3% + 15-30c for each transaction.
'High-risk' (of a high-level of chargebacks) merchants pay card fees of 5 - 8% + 20-40c for each transaction
This includes: Travel , Booking, Airlines, Gambling, Gaming, Adult entertainment & Firearms businesses.
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So your average merchant is going to be saving a decent amount, at least 1%, most likely more, especially for businesses with a low average-purchase-price. What any Nano merchant provider needs to do then is convince each merchant to implement a discount for customers using Nano, then the merchant and customer both win.
Example:
Coffee Shop ABC has an average price of products sold of $5
Their card provider charges them 1.5% + 20c per transaction which means they pay ~27c per transaction in fees or 5%.
Then they implement Nano. Now they get charged 1% for auto-conversion to Fiat and they nor the customer have no other fees to pay because there's no network fees.
If they get 500 customers a day, they would save $3,000 a month if all their customers were to use Nano.
Unlikely but those savings would be enough to convince most businesses to both implement Nano and incentivize customers to use it. Even if they initially gave customers a 2.5% discount (and lowered it over time) to use Nano, the merchant would save 1.5% and the customer, 1.5% (after gateway fees) per transaction.
TL;DR: Both merchants and consumers can save money by using/accepting Nano