if btc retraces 30 to 40 percent when it hits 13k to 15k what will happen to alts will they fall as well or will they go up or how would it play out?
Alts seem to get funded well only when Bitcoin is "loaded" and the money flow into starts to slow down.
When Bitcoin jumps alts fall behind; when Bitcoin falls, alts also fall, sometimes even more than Bitcoin.
So for your use case (bitcoin falling) I'd expect the altcoins fall. However, if Bitcoin will not fall and will only slow down, then the equation changes completely...
If this is expressed through equations, then the current initial wave has slightly different initial values of the variables.
Namely. Until spring 2017,
Bitcoin held about 80% of the market. Now it is 50-60%. In addition, many new altcoins have now appeared, some of which are dying and some occupy a market share. Now the behavior of altcoins may be different.