It's very hard to know whether sidechains will help or hurt ethereum... You could put an ethereum clone in a sidechain, although there'd be downsides to this...

It's very hard to know whether sidechains will help or hurt ethereum... You could put an ethereum clone in a sidechain, although there'd be downsides to this... It's hard to know how mining would work for such a chain, it would have to work differently than either bitcoin or ethereum mining ("merge mining" alone won't work due to the fact that ethereum has 50x the block rate as bitcoin) and sidechains have extra mining costs that need to be obtained somehow (such as through a "wealth tax" on unused accounts). On the other side, ethereum itself could host bitcoin sidechains as contracts, adding value to the ethereum network. My own best guess is that sidechains will be a net positive for ethereum adoption, but a net negative for the ethereum currency market cap.