I would say that if BTC hits 100k than alts will also explode. People would stop investing in BTC and look for alternatives like NWC, SNX, MArgiX, NEO etc..
If in any case (i hope) btc hits 100k we will all be rich

The conditions in the market have changed dramatically since the last bull run and you are expecting that altcoins behave in the exact same way that we saw back then but I have my doubts that will happen.
If bitcoin begins to go up in value then it is possible that some of the most popular altcoins will grow a lot as well but it is also entirely possible that we see something similar to what happened during this year, in which most altcoins grew up in value against the dollar but when it came to bitcoin their value went down