The SkyGuardian (aka Sky Guardian) might turn out to be cheaper than relying on sonobuoys only dropped from manned P-8s. See this DefenseNews report of
January 18, 2021.
Australia has selected the Sky Guardian UAV. Presumably the US military would also buy it, if its a successful sonobuoy dropper, fixed sensor and (maybe) weapons carrier.
Artwork of future Sky Guardian dropping a sonobuoy. It appears to be networked with a P-8 in the upper left corner. (Courtesy DefenseNews)
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