Simply put the most of the alternative cryptocurrencies are fake /scam/fraud/ponzi, I don't see any future for any of them except
The first 20 coins in market.
Which sums up the issue in totality: the biggest issue of altcoins is trust. Longevity, and motivation. Bitcoin was built with no immediate profit motivation. No ICO, no crowdshare. And it been around how long, just now making significant traction? This is the definition of trust, and essentially people are going to stop chasing the blatant cash grabs and possibly support the alts that have has time to garner 'trust'. With all the coins already out, you really have to question the motivations of someone introducing yet another one.