Managed Pools - (name TBD - second generation Investment Pools), with all current Investment Pool features, but better scaling to higher token counts (e.g., 50). They will also have advanced features, such as circuit breakers (restricting trading to price ranges), different types of management fees, and the ability to add/remove tokens from the pool.
There will be additional flexibility for pool ownership, likely in the form of pool owner template contracts that can be deployed as the immutable pool owners. For instance, there could be a "Gauntlet" template that allows a third party to control swap fees, while reserving all other permissioned functions to a different multi-sig. That way Managed Pool issuers could contract with Gauntlet (or another provider) to provide a fee optimization service for investors.