It might not be this year anyway, because the last quarter of this year will be full of bitcoin fluctuation and we will still have series of corrections, I think it would be until the halving of bitcoin next year before altcoins can start their own season when bitcoin is going sideways and I am sure that the coins that would be affected would be much more than the top 50 coin in the coinmarket.
if theres no such news and eventually this do happen recently on that 2017 and 1st quarter dump of 2018 and talking back on past years retracements.
For now when it comes to altcoin investment decision then it will just matter on which one we would accumulate on.