SC's are clearly altcoins.
Different class. 'Sidecoins' are most accurately described as a proxy for Bitcoin. Use of sidecoins impacts the macro-economics of Bitcoin in pretty much exactly the way that use of Bitcoin itself does. 'Alts' are completely stand-alone and as such are competitors. 'sidechains' are more like colored-coins and in some ways it might be argued that this is what they are at their core.
i see sidecoins as inflationary. the author can choose any issuance or inflation schedule he pleases to be backed by scBTC. when viewed this way, the entire fiat money system could be viewed as a sidechain with USD as the sidecoin with gold backing at least before 1971.
brg444 and Adam spent months teaching us how any type of coin ala Truthcoin can hitch themselves to a SC in addition to the migrated scBTC. in fact, have you EVER heard Blockstream place any type of restriction on what kind of speculative asset can be supported on a SC? answer: no. they are a form of dilution, hence inflation, to Bitcoin and will turn Bitcoin into a WoW trading platform.
The economics of 'speculation' in a full-peg environment are no different than people simply using native Bitcoin heavily. People are perfectly free to speculate in native Bitcoin, and to date that is what has happened in the economy mostly I think.
You bloatcoiners may have plans to implement control measures in XT which preclude speculation as far as I know. With the infrastructure needed for tainting, control of speculation would, in fact, be tenable.
edit: slight (between ngix gateway errors.)
no, SC's encourage speculative money to chase sidecoins, scBTC, and/or any other speculative asset they choose to sell on the SC like Truthcoins. given that these SC's are bound to be less secure, they will have much greater failure rates than if they just bought BTC itself or invested in businesses that deal in BTC directly. what we want instead is for speculators to invest in BTC itself to drive the market price much higher. which is actually needed to allow large $million tx's to occur on MC w/o causing volatility. that, or invest in merchants/businesses that can service the userbase growth that a no block limit will encourage.