It's unlikely this will happen until mainstream adoption occurs and a few select altcoins find some real-world utility. There are probably a few niches where some coins might shine. Only coins that find an actual
purpose will stop tracking BTC and begin some natural price discovery. The rest are just speculative tokens and will either continue follow the market leader or become worthless.
It may hurt Bitcoin initially, but it's time to disconnect all BTC/XXX pairs and let the shitcoin market take care of itself.
Short of mass-collusion, there's no way to achieve this. It'll either happen by itself, or not at all. I don't think we get a choice in the matter.