Is there a way to predict somehow the required storage for a specific blockchain? I'd like to store a blockchain or two in my computer. Blockchains are pretty heavy (I took over 3hs to download GameCredits blockchain, and is one of the smallest blockchains, I guess). My main fear is to not be able to keep using my pc to store the blockchain (e.g. this applies for others like Litecoin).

Is there a way to track current blockchain storage sizes and predict how much space will I need the next one or two years?
This depends on a number of factors,

1) The amount of transactions 

2) How the blockchain will be compressed in the near future.

Now as i'm not quite familiar with the altcoins you stated, I can't go in depth about their compression development, but it would be fairly easy to find out what the MAXIMUM size of the blockchain could be.

Simply calculate every block as if it would be filled up with transactions ( maximum size), and multiply that by the amount of blocks  for/until the next year.