If iSCSI implements file-locking properly and LR cannot detect it as being different than local storage then iSCSI could help users wanting to use LR in single-user mode with the database not on a local drive. For Windows, subst will also allow with this.
This is entirely different than LR facilitating multi-user photo editing with a single catalog, which requires a client-server database hosted on a database server and LR being written to handle user-editing conflicts. I suspect the market for this is much too small to be cost-effective for Adobe to develop such a product and the multi-user environments to buy and maintain such a system.