Once you understand that sidechains are just that "sub-coins to Bitcoins 21M controlled supply", then it is natural to see sidechains as part of the original Sound Money plan. They simply offer a mechanism to increase functionality without a hard fork. Period
But these guys think that sidechains are somehow reinventing the altcoin threat
They don't care or wanna hear about the innovation of 1:1 two-way peg, they are busy fighting the inexistant altcoin threat
Exactly... The only feature a sidechain can add to the existing altcoin concept is decentralized exchange. If this is the only thing holding back the flood of investments into altcoins, than all of us primarily holding Bitcoin are fucked, because sidechains or not, it is coming.
Apropos decentralized exchange, I found this interesting bit in the sidecoin white paper:
"Appendix C Atomic swaps"
http://www.blockstream.com/sidechains.pdf
Page 26
Basically a trade where either both payments succeed, or both payments do not succeed. (Risk free trading).
I see no reason that this requires different coins where value is pegged together.
Is it possible to do this today without changing any of the two coin types?