1) Native implementation
2a) Counterparty with a metacoin ("native" coin in the bitcoin Counterparty (XCP)/Mastercoin (MSC)) created by burning (i.e. destroying) IXCs
2b) Counterparty with a metecoin "distributed" to all IXCoin owners according to their IXCoin ownership at a certain block heigth (launch)
2c) Counterparty with no metacoin. Betting etc. implemented by allowing bets to be offered in any user definied asset/currency (instead of using a metacoin).
2d) Counterparty with no metacoin. All features requiring escrow (betting etc.) stripped off. This is pretty much equivalent to ColoredCoins.