Replacing Cryptonote rings with RingCT value hiding is probably incompatible with microtransactions-at-scale in all current block chain designs because (including Monero) they don't remain decentralized at-scale, but not that was Monero's focus any way:
Although sub-penny microtransactions are not economically feasible with credit cards
nor current crypto-currencies because the fees are too high, these systems could in theory lower costs enough to lower fees to a percentage of the value of the transaction (
assuming transaction values are not hidden with homomorphic encryption, because in which case the oligarchy centralization inherent in these system
has an incentive to raise to fees to what the market will bear cutting out lower valued transactions).
...
Dunno if i grasp your intention at full spec, but microtransactions we´re never intented to be populating the mainchain --->
https://getmonero.org/design-goals/Side-chains and daughter-chains (even if merged-mined) have very negative implications on security for the main chain.
Nevertheless, the core issues of scaling the design still need to be solved for the daughter chain, which no one has solved yet. Or you go off-chain, which has another set of insoluble issues.
So we might as well just say Monero isn't going to do anyone-to-anyone-spontaneously microtransactions-at-scale. Until I see a detailed technical refutation, I will assert that from my knowledge base on this area of expertise.
Edit: RingCT I presume is optional. So those who want to present the value of their transaction, so that an oligarchy could apply a lower fee (without destroying their ability to charge the highest fee the market will bear), would still work for users that chose not to hide the value of their microtransactions.