I guess they are already independent of each other and what drives them is their own project developments, progress in the products an services and rest of the factors but limited to that particular coins project. They never get affected with other altcoins, because both of them carries different environment for themselves. With the current situation bitcoin is up because it is breaking its own resistance, with the Q3 end coming to nearing it is very much agreeing thing that most of the people start investing into the Bitcoin and thats what causing the sudden hikes in the bitcoin. Altcoins will follow too because but people will fill up the bitcoin first and then alts.