USN are keen to replace the Super Hornet with F/A-XX apparently.
The US Navy has barely started to even conceptualize the F/A-XX and there is very little money in the upcoming budget for it. Most optimistically, the USN couldn't expect any prototype to fly before the late 2030s and that is extremely optimistic. And optimism is not something one associates with the schedule for the development of a radically new sixth generation fighter.
I disagree! The Super Hornets will reach the end of their service life (9000 hours) in the late 2020's early 2030's depending on operational tempo. The F-35 while a great aircraft isn't the be all and end all (after all it paid a huge price aerodynamically and conceptually in order to include the STOVL requirement) , and I don't see the USN relying on only a single aircraft type for strike/AA roles. By then the F-22 will be over 25 years old as well.
By the mid-late 2020s - China, Russia and potentially India among others will have advanced 5th generation fighters and UCAVs that come close to matching existing aircraft (likely in larger numbers - remember the F-22 final procurement tally is 187) . Anti-access/area-denial (A2/AD) capabilities of many nations will be highly effective. Advances in multi-band radar and high speed computing will mean the stealth technology on 5th generation fighter aircraft is no longer the silver bullet it once was.
The geopolitical situation will have changed to the point that we genuinely are in a multi-polar world (with serious competitors to US primacy) rather than uni-polar world that has existed since the early 90s. (This among other factors will create a sense of urgency that was not there for the F-35).
The delays,cost blow outs and problems of the F-35 highlight the long lead times required to field an advanced aircraft with a significant qualitative edge, and conflicting requirements (eg Airforce,Marines,Navy). I do not believe the US will make the same mistakes again, or accept a capability gap/loss of qualitative edge. They can't afford to or their multi-billion dollar carriers will lose much of their teeth. Remember carriers despite their weaknesses are a key instrument of national power, and domination of the global commons.
3D printing and associated technologies will make development of a 6th generation fighter a lot more effective and efficient than the previous generations. What historically took weeks/months will be done in days/weeks (see here -
Link).
Once the F-35 is at full rate production , I am tipping we will see a lot of movement in this space (SH replacement). Air to Air/ Air-Ground combat is not going anywhere soon - if it is the F/A-XX,UCAV, or something else (potentially radically different) that is another story. But in IMHO the USN will replace the Super Hornet with a new aircraft other than the F-35, and we should too.