Not just then. I was just reading about the CL-84 (in Convair Advanced Designs 2) and the larger 84-8 design for the SCS had a four hour patrol time at 150 miles and a top speed of 440 mph. Imagine that (or its successor) in ASW, AEW, COD, etc. operating from Queen Elizabeth, or Charles DeGaulle, or Cavour, or Izumo, and the like.
But to the scenario, I suspect it would make small carriers really attractive, and there might have been a proliferation of them among navies that had carriers but had to give them up. ASW carriers could patrol much larger areas, and much further from the carrier. Small carriers could act as fleet carriers, with AEW and fighters, perhaps supplemented by Harriers for CAS support. Essentially a return of the WW2 CVE, used in ASW, amphibious assault support, CAS, even the odd fleet action. The 200 and 84-8 wouldn't the capability of the Tomcat and Hawkeye, but they'd be a lot more effective than Sea Harriers and helicopter AEW.
I also suspect the XV-15 would go nowhere; there was also an assault version* of the CL-84-8, which had capacity of 22. Given it would have been over 100 mph faster, the XV-15 wouldn't look near as attractive. And medium tiltwings could have been deployed 25-30 years earlier than the Osprey.
What I really wonder about is what second generation tilt-wings would be capable of, and what a follow up to the 200 (Vought TF120 anyone?) would look like. And the real kicker, what might VSTOL look like today with potentially a couple more generations of VSTOL production and development?
*The full list in the Convair book for the potential 84-8 variants is ASW, AEW, Tanker, COD, Assault Transport, SAR, and ASMD (anti ship missile defense). There was also an attack variant of the earlier and smaller design.
