What happens if one of these side chain alts becomes very successful (for example is supported by the banking system) and begins to draw a large number of bitcoins in circulation into lockdown.
many of us will have a bad time running around gathering up cold storage wallets to transfer to the new SC. possible privacy leaks galore, not to mention risk.
lol, SideChain is backed by bitcoin. SideChain is protocol. SideChain is only temporary. The only way sidechain can outperform Bitcoin is when Bitcoin security is broken and SC's is not.
That's right. To state it clearly, there will be an arbitrage opportunity. Buy BTC, transfer into SC, sell SCBTC, buy BTC. So the price of bitcoin will be lifted with the added value sidechains bring. In this sense inca, the child chain can never "destroy" Bitcoin even if it ends up carrying 99.9% of the transactions.
To address Cypherdoc and other people's "what if" questions about the future, "we" (as in the Bitcoin evangelizing crowd) have been selling bitcoin as the "TCP" (or "HTTP") of finance -- anything can be layered on it. That is the "promise" of Bitcoin as a world currency. But you can't really layer applications on top of it like you can TCP or HTTP, except in a very small 40 byte per txn area, and in the awkward colored coin concept. Sure, you can make an independent app that happens to accept payment in Bitcoin, like a centralized storefront. But that is hardly layered "on" the Bitcoin protocol.
Sidechains IS the technology that really lets us build anything "on" Bitcoin. Because the value of Bitcoin is NOT in the code -- otherwise running on testnet and/or altcoins would be much more valuable. The real value programmers want is having a digital, supply limited (etc etc) token with programmable behavior that HAS VALUE from day one. (But right now Bitcoin does not really have "programmable behavior" -- all you can to is transfer it)
If sidechains don't happen I will still be invested in Bitcoin as a diversification especially given the indebtedness of important governments throughout the world. However, I would revise my "end game" estimate downwards by 3-4 orders of magnitude (1000-10000x), esp. if the block size is also not increased. I would expect, best case, Bitcoin to become crypto-"gold". Held but rarely used. Worst case, some highly functional altcoin takes over and BTC's value dwindles to 0.