Roger - I'm not a doomsayer, simply one who has spent many years carrying out many searches, from Wessex with no sensors but the Mk 1 eyeball to the Sea King with a FLIR/TV turret and an autopilot that could fly the aircraft around a search area (Mk3A).
Inevitably, technology improves the quality of the sensors used but the SAR helos will have the best available anyway with the added benefit of having human beings to interpret and investigate sightings immediately.
There may be one search in a couple of hundred where a drone may be of limited additional use - unless you want to use the drone instead of a helicopter to be able to say you have 'searched' an area and tick it off the list.
Far better to invest the money in improving the search planning programs so they can produce more accurate, smaller and more precise search boxes rather than the blunderbuss approach often used at the moment. I lost count of the number of times the CG computer created massive search areas that were so improbable and easily disproven by assets on scene. Will the UAVs be able to make decisions to amend the search area based on the actual (rather than predicted) conditions on scene, local knowledge of tides and races etc?
I like new technology but UAVs are not new, the sensors they will use are not new and I would far rather have one more helicopter to search with than several UAVs.
Just because it looks new and shiny and AI is the new religion for techno investors, doesn't make this a good or practical idea.
We used to have Sea KIngs with a phenomenal radar that could detect a periscope in the water (or fins of dolphins and whales as I have seen before) - this was replaced with a lesser system because 360 radar was old fashioned and dinosaurs like me had to move on.......