side chains is not the solution..

for instance.
1. side chains is like saying 'gold is a natural and rare material. but in 2016 it can now be made in lab in infinite amounts' - goodbye rarity
2. side chains are other blockchains... so whether you do a transaction on bitcoin or a second chain.. the data has not changed or decreased, its just moved. but now instead of one blockchain to fill up a hard drive.. now miners have to worry about multiple blockchains bloating a hard drive.
3. by mining more than one chain, will dilute the hashrate/difficulty as the hashes dont just protect one chain, but now have to protect multiple chains
4. sidechains wont just be a problem for miners, but also users wanting to run full-nodes. as explained in point 2. which will cause a dilution of people wanting to run
full nodes because they would have to store X*32mb blocks per 10 minutes. instead of just 1*32mb blocks per 10 minutes.

the only positive of sidechains are only for the creators of these altcoins. who can premine an altcoin and then sell it 1for1 for bitcoin..