Whats necessary to offer instant trading of EUR:bitEUR ?
I think liquiity really on both sides, and it is really same as with usd/bitusd, also her ewe need liquidity also in order to provide support for nanocard with those two currencies supporting it.
Once the wallet version with Bitshares 2 is up and running you are supposed to have Biteur automatically in your account when you deposit EUR, and same with USD, so I dont see it even needed at that time.