Mini-subs definately have their uses, as do UUWV. However, they also have a number of limiting factors, which I don't see being overcome any time soon.
For mini-subs, they are distinctly short-ranged by virtue of their size. This forces them either to operate from a nearby home port, or a replenishment/sub tender/mothership. This in turn tends to dictate that most anti-shipping operations will be defensive. Similarly, the small size of a mini-sub also limits the amount of armament carried as well as the capabilities of the equipment. As I understand it, the sonar arrays found on SSK and SSN are larger and capable of engaging a mini-sub that it detects before a mini-sub would be able to engage an SSK or SSN.
The areas where a mini-sub could excell in are things like covert insertion/extraction, where the small size is an aid in operating in restricted waters. Or covert mine deployment, again, where the small size can allow submerged operation in shallow areas. Lastly, defensive anti-shipping, close to a home port. By close, I mean close enough so that the mini-sub can operation off of an AIP system (if there is one small enough) and/or batteries for the duration of the engagement and the time needed to transit to & from the home port without surfacing and/or operating diesel engines.
As for UUV, I don't particularly see a combat type being deployed just yet, at least not for ASW work. There are issues with C4ISR that need to be resolved before a UUV would become combat effective. Among them is the datalink between the UUV and the command center. In order to be effective, the datalink needs to be reliable and secure, without giving away the positioning of the UUV. It also needs to have sufficient range for the UUV to operate effectively as a combat vessel. I believe one of the current preferred communication methods for UUV or ROV is a tether, not something that I believe would lend itself to combat.
Still, given time, who knows where things will end up.