The proper solution, is the nobody should EVER be removed from an instance because of other player actions. This will be the only way to prevent malicious use of the partying system, and give everybody a fair chance to play how they want.
That means, if a party is split by a kick, the instance should be replicated for the split parts.
Of course this will allow the replication of an instance that is in a desirable state, which can easily be exploited. But this kind of exploitation should be considered an acceptable and mitigatable risk.
Mitigation involves, restructuring rewards so that there is no time where an instance is in a highly preferred state. Most of the times a dungeon is in it’s most prefered state, just before the final boss as the majority of the reward is earned by fighting and killing that boss. One good way of restructuring the rewards is to distribute more rewards across the entirety of the dungeon instead loading it entirely at the end.
In the same vein, dungeon currencies should be rewarded based on the player’s actual participation throughout the dungeon (sorry to dungeon purchasers, but coming in at the final boss, and fighting just him should only be worth a fraction of the tokens. Dungeon selling is not supported by the game.). Perhaps 1/2 token for each gw2 gold medal event, and 1/3 token for silvered and bronzed events throughout the dungeon (or other fraction depending on the number of events). To reward completion, of course, these rewards would be withheld until the final boss falls (but if you are forced into a copy, your rewards follow you).
Other tools for mitigation is to apply a sort of DR and have an instance reward entropy if an instance is copied too many times. This will also add consequences for being unable to work with a party that you joined. Rewards can be docked to players who are affected by the party kicking system or choose to use it.
The solution is to simply have a game where the manager’s of the economy do not have to worry about it being wrecked because an instance’s state can be copied. Rebalancing them in this way will also be helpful in revitalizing the way in which people can play dungeons. If the designers of the game can make it so that in game economy issues are separate from the mechanics of starting, stopping, continuing, and finishing a dungeon, then, the game will have a platitude more flexibility when handling how to deal with instances along side the party systems and other potential technical and network issues.