Microfinance: Definitely yes. Interoperability of blockchain technology offers greater control and transparency.
Micropayment: Low cost micropayment will be posible when some state issue CBDC (central bank digital currency) even as a new form of money as stablecoin (digital currency conected to fiat currency).
Microinsurance: Yes. At many use. Smart contracts offer many ways for the parametar insurance or insurance per use.
Then, the interoperability of blockchain technology offers a good tool to fight frauds in insurance. Bigger efficency in P&C insurance . Reinsurancy is also part of the insurancy could have a lot of benefits using Blockchain technology.
I wrote an article about that in the magazine "World of Insurance" (on bosnian: The World of Insurance) on bosnian language. If you wish, I can send you and you can try translate it.
Absolutely, however, aside the benefits, issues related to the cost of diffusion, legal requirement fulfillment, and the readiness of end-users to diffuse the technology are some of the challenges.
I should point out that this is a Proof of work protocol, which is a relatively huge energy consumer. But the Proof of stake protocol consumes much less electricity, for example, a complete network that conducts Ripple cryptocurrency transactions consumes less electricity than the Visa Inc payment processor. This is important information, as Blockchain technology is often misidentified with bitcoin cryptocurrency in terms of energy consumption.