2019 will have many of big coin as Telegram, Facebook... What will happen to the remaining altcoin?
There has only been rumours about facebook developing a cryptocurrency, it would be massive if that happens, but there's no point deliberating on a rumour.
Telegram hard a very successful ICO, but it's yet to hit the exchange, could do so next year. But, I don't think one or two new coins will have much of an impact on the other altcoins.