First thing first, if Bitcoin reaches 100K there will be SOME Altcoins that will as well increase. Alts made out from fork meaning they have been created from the scraps of bitcoin from imagery of it. Although if it reaches at the certain time, it will eventually fall from its place. It is not that in certain price forever, so, maybe the following weeks or months it will eventually fall. On the other hand 100k is a big thing mate. It will be a hard time for bitcoin to reached that.