True.
Its hard to judge because there hasn't been anything like this since the dotcom bubble in the 90's
I believe it was about five or six years before everything started to fall apart (1994 to just after 2000 before a lot of big companies went bankrupt)
maybe someone can provide a more accurate timeline on this.
but the dotcom bubble was based on actual functioning companies, even if they were crappy ones. they had employees, products, services, serious investors and even customers and actual utility. that all takes real time to screw up and die.
icos are dust built on even more dust. their 'bedrocks' are nothing than speculative playthings, let alone their ico offshoots. even bitcoin has a long, long way to go before it's anything more than speculation.
During 20002002, the bubble collapsed. Some companies, such as Pets.com and Webvan, failed completely and shut down. Others, such as Cisco, whose stock declined by 86%, and Qualcomm, lost a large portion of their market capitalization but survived, and some companies, such as eBay and Amazon.com, later recovered and surpassed their dot-com-bubble stock price peaks.[2]
See BTC as the ebay or amazon, they surpassed their dot-com bubble peak by more then 100 times.
Some survived but all the companies without any real income stream died very quickly. The ones that survived and thrived were the established players with lots of money behind them. I agree BTC will be one of them but I'm not sure how many of these altcoins there will be, I think about 90% of them need to die for a healthy market to go on.