At current prices, STEEM certainly has some room to increase in value. I am thinking that long-term STEEM could trade around a price of $10. It is a working coin, available to be earned from the masses. So there will always be plenty of people willing to sell all they get to buy something.
I would say the coins to be in the base are there for a reason, that they have shown themselves to be worthy. It would be smart to have them as you need stability. Not all growth coins will grow as you think.