Hey @AtomTanNZ great question!
There’s still no specific public details on the exact mechanism that will be used for the fee handling, but of course there has been a lot of discussion internally.
From a high level, one idea was to have an auction system in place that would auction off fees at a discount that could be bought with ICX - and then that ICX would be burned.
For example:
- Transfers from Binance Smart Chain (source chain) would collect fees in BNB
- Auction would occur on the ICON blockchain to purchase these BNB fees with ICX
- People would bid on the collected BNB fees until the auction is complete, with the BNB likely being bought at a discount (for arbitrage)
- “Bob” wins the auction and pays ICX on ICON, then claims their BNB on Binance Smart Chain
- Bob’s ICX that was used to purchase the BNB is now burned
To answer your questions, with this mechanism:
- Yes, this would be handled via smart contracts and would likely use xCall as well
- The buyback of non-ICX fees wouldn’t be instantaneous as they would need to be auctioned off over a certain period of time
*when ICON is the source chain, ICX is the fee that is charged - in which case the fee (ICX) would be burned instantaneously
With that being said, this method is not finalized but I wanted to give you a brief overview of how the fee handling + buyback could occur