I think you are right about eventually prices will be determined more on fundamentals than purely speculation, but I disagree with how quickly that will happen.
I think we will have another 'everything go up' event when the bitcoin ETF gets approved, even though that should only impact bitcoin.
People will likely try to jump in front of the next coins to possibly get an ETF, coins like ether and a few others will likely see an influx of cash trying to front run an ETF.
That may bleed out into many other coins as well where everything goes up and it feeds on itself.