In principle I think rented subnets are a good idea. We could do with a more diverse set of subnets, where each one meets nuanced criteria (such as regulatory compliance, but other things come to mind such as building subnets where all the node providers have a certain amount of staked tokens, or much larger or smaller subnets, subnets specialised for running certain workloads like LLMs etc.).
It’s already the case that new subnets can be created by the community. I think the trouble is that there’s typicall not a good way for the voting community to gauge whether or not there’s enough demand for a certain type of subnet (will demand be enough to pay for running the nodes).
I gather that the point of subnet rental is that the proposer for the new subnet fronts the ICP for rewarding the nodes for roughly 6 months of compute, and keeps topping it up. This way it somewhat removes the concern about there not being enough demand, as the proposer has put their money where their mouth is.
I think it’ll be interesting to see how this goes. If there are pitfalls they can always be improved. If it works well I have a feeling this could be a great feature for the IC.