I have been and avid OSRS player for years now, and truly miss the ability to CO-OP Slayer with friends. Can we please consider bringing it back, I am rank 93 Slayer and would love to enjoy the final levels to 99 with friends. It is a very lonely skill.
Good news to you in RS3, you won't miss CO_OP Slayer. It is communal and rewarding as usual. You can also slay with clanmates for even more bonus in RS3 too.
Yes I do believe jagex wants to eventually bring it back if possible. Judging by the wiki it was last removed due to bug abuse so clearly that needs to be resolved first. Fingers crossed