Hard to say. You're talking price ratio. There's also the market cap ratio. I don't think Eth will ever surpass Bitcoin in price ratio but it might surpass it in market cap ratio. If that happens, we will have "the flippening".
In the last bull run, Bitcoin peaked on December 17, 2017. It was about a month later that Eth peaked on January 12, 2018. That was about a 14:1 price ratio - but around a month apart. In fact, most of the alts went strong for about a month after Bitcoin peaked. I think some were getting out of Bitcoin and investing in some of the new alts that were still zooming up. Eventually, many got out of the market altogether and therein followed about 2 years of down, down, down and the bear market.
Currently, using the 16:1 ratio, if Bitcoin goes to say $160K, then we should expect a $10K ETH (but it may happen a month later). I think that is possible. No guarantees.
Colin Talks Crypto did an
interesting video (run time 6:56) about how to know when the Bitcoin peak is at 90% to 100% of where it is going to go - maximizing the profit taking. He and another fellow created an index to forecast when the peak arrives. Roughly, in 2013 the Bitcoin peak was between 90% and 100% for 24 days. In 2017, the Bitcoin peak was between 90% and 100% for 23 days. So, if history holds true, there will be about 3 week window to snag max profits with the one day peak right in the middle....