The Navy has plenty of airplanes, and will soon have the same airplanes as the Air Force. I don't see why it makes sense to make a missile just for boats when the USAF, USMC, and USN are all using basically the same aircraft as far as weapons are concerned. Everyone benefits equally from a missile that can be carried by F-35.
So those missiles will be carried externally? So everything is going to be Carrier Strike Group related?
A VLS missile would need to fit within Mark 41's dimensions, which are pretty constrained for any sort of high performance supersonic missile.
So far the USN doesn't really have much of a better option than Tomahawk and possibly LRASM for higher end threats, but Tomahawk seems perfectly adequate for knocking out S-400s or whatever. Something like AGM-183 would too big to fit in current VLS and require making larger ones, or using some sort of external box, both of which have their own limitations. Bear in mind this is for a platform that goes slightly slower than an LA mid-week morning traffic, at best. So you've mostly negated the benefits of the hypersonic weapon.
Something like F-18E/F or F-35 is probably going to have to carry a hypersonic missile externally, yes. "Everything being Carrier Strike Group related" more or less summarizes the past 40 or so years of US Navy thinking about strike: it's an extension of the CVBG and its escorts. The escorts aren't lacking for strike at all nowadays, nor will they in the future, since Tomahawk is going to get the new Block V upgrade soon. I have no idea what ripping out Tomahawk cells and replacing them with ARRW cells will do, but giving ARRW or airbreathers to the carrier will give the CVBG more strike potential without sacrificing its existing strike load.
A CSG performing strike is not out of the question, but it would hardly be the first choice. The first choice would be B-21 with JSOWs, or B-52 with ARRW, or something similar. The Air Force is the ideal rapid response strike force because they have actually long ranged aircraft that can carry big weapons. If the USAF ever gets a internally carried, air-breathing hypersonic weapon, it will probably be sized for F-35 though. Which means the USN can use it. Which will be good.
Since the USN is unlikely to ever get a long ranged carrier aircraft in the near future (something comparable in performance, preferably better, than ATA) I don't see how that will change much. It's going to be Super Hornets and a handful of F-35C's for the next couple of decades.
Something like AGM-183 on a submarine would probably make the most sense in the future for the USN, as far as contributing rather than sitting on the sidelines. It should be relatively simple to put a few ARRWs in a VPM or something than finding room on an already overcrowded DDG's deck, or ripping out Mark 41 modules for a new VLS system, and a submarine is more likely to be in place to actually attack things, because US subs are fairly stealthy and can be expected to be able to get close to enemy shores.
X-51 and AGM-183's fin-related problems were dropped in the same post by someone, as if they were related or something, and not separated by about a decade.
Anyway yes, all those tech demonstrator programs were successful and delivered what they promised.
LOL. Okay, do you have any actual evidence of that? The BEST X-51 did was fly at Mach 5.1 (after being boosted to Mach 4.9 by the ATACMS booster). It did not reach Mach 6 as intended. It barely accelerated under scramjet power. It never did fly under power for the full 5 minutes as I recall. And that, the most "successful" flight, almost didn't happen. The people in charge were literally almost too scared to try. "What if we fail?" Well, you can't fail if you don't try I suppose.
HyFly was an abject failure.
RATTLRS went nowhere. (No, it wasn't suppose to be a "jobs program". It was supposed to be a Mach 3 cruise missile.) If you can't think of a use for that just look around. It's obvious.
X-51's JP7 scramjet propulsion is being continued with HAWC.
HyFly was a "failure" because it was an exotic engine system. Considering Boeing recently received funding to bring back the DCR engine for ground tests, although I doubt it will fly again, I don't really see how it failed at anything. It proved that the technology was too immature for use in a weapon. That's really all it set out to do, since it's DARPA. It would have been good if it had done more, but proving a technology requires more time to bake is a good result. It lets you eliminate the blind alleys.
OTOH RATTLRS was never going to transition to a weapon system. DARPA doesn't really fund that, that's the services' jobs.
The point of RATTLRS was to test the YJ-102R, which was an evolved version of a SLAT competitor's engine from the early 1990's. It had more promise as a supersonic target drone but perhaps it was too expensive to produce, or more likely the services never identified a need for a relatively slow Mach 3 "missile" or whatever Lockheed-Martin was hoping they'd buy, when they had far better performing weapons on the horizon, like AGM-183. Or for that matter, better performing target drones, like GQM-163. That said, RATTLRS did complete its test cycle, the engine apparently worked fine.
However, this is hardly surprising, since the YJ-102R is essentially a slightly more fuel efficient form of a J58. Not exactly bleeding edge, nor was too much performance being asked of it. Not exactly sure why you're surprised no one in DOD picked up on a missile that was not much better than what has already been achieved by something like P-700 Granit in the 1980's, after decades of funding scramjet and Mach 5+ hypersonic weapons. The answer should be obvious.