Bitcoin started to be mined with asics on 2013, bitcoin value were at 40$ on march 2013, bitcoin went to 20k on december 2017, a 500x value, so if you say that asics makes a coin value to drop, you can see what happened with bitcoin and see that for bitcoin it was not true that asics were something bad, maybe for gpu miners on 2013 asics were bad news, but not for new asics miners who started a business and not for bitmain, and not for the bitcoin value.
Your logic is so fucked up.
ETH always was a GPU coin yet it managed to be the second big crypto in 2-3 years.
ASICs are thievery, nothing else. What ASIC manufacturers do is, stealing your right to buy a miner. Because when an ASIC manufacturer decides not to sell an ASIC, there is nothing you can do about it. If bitmain, bitfury, halong decide to not sell their HW so they can mine all the coins (bitfury is doing this pretty much btw) what would you think about that? While a GPU/CPU company has to sell their HW to their customers no matter what, ASIC companies can completely ignore this. Fuck ASICs.
Back to the topic.
There are 2 coins which keep GPU mining alive today. ETH and Zcash. If one of them dies, the damage will be huge. Tbh i dont think zcash has the power to carry all the available GPU's. Only Eth can do it and when it switches to PoS ot will be over for us.