"The thinking on sidechains might be shifting.

While historically seen as an avenue for experimentation and increased operability on bitcoin's network, the conversation is now framing the technology as a possible solution to the digital currency's long-standing scaling debate.

The idea behind sidechains is to allow many coins with different sets of rules to be tied to bitcoin. For instance, one sidechain might feature the advanced privacy of MimbleWimble, while another might allow for much larger (or even smaller) block sizes."

http://www.coindesk.com/are-sidechains-a-better-solution-for-bitcoins-scaling-debate/

I've been saying this for years!