The Strike Eagle was always intended as an F-111 replacement, so the writing is on the wall for the F-111. And it’s likely they won’t be produced at the same low rate they were IOTL; the full buy of 392 will probably be done by 2001 just like the reduced buy of 236 the Air Force wound up getting.
F-111s will by necessity stick around longer, but by the early 2000s I expect them to be all gone.
IIRC 24 Type 23s were initially planned, to give the Royal Navy 38 frigates and 50 surface combatants overall.
I know that the Strike Eagle was intended as a replacement. Though I could see the Strike Eagles operating as complements to upgraded F111s for longer then you suppose.
Use the strike eagles as escorts to provide fighter cover and SEAD capability while the F111s act as the bomb trucks.
Especially if the US still get's involved in some COIN type wars even with the Cold War. Having the cheaper to operate F111s acting as bomb trucks to save lifespan on F15E air frames. Sort of like how the WOT ended up using a lot of air frames from the B52s/B1s and the like newer more capable and expensive aircraft.
If the Soviet Navy also grows to be a bigger menace perhaps we might see modified/upgraded F111s rededicated to maritime strike using cruise missiles and the like. Say bassed out of Norway to counter the North Sea Fleet, from the UK or Denmark or southern Norway to counter the Baltic fleet, Out of Greece, Turkey or British bases in Cyprus for the Black Seas fleet, and say out of Alaska/Okinawa/Japan/SK/Philippines/ Guam to counter the Pacific Fleet and potentially the Chinese one as well.
I've been wondering about a TL where say instead of the B1A/B1B instead the FB111/F111 is stretched, heavily modified, perhaps different engines, more integral electronic warfare suite, increased in size and turned into something like the TU22M. Moreso something that's designed from the start to be capable of not just nuclear roles but conventional ones capable of carrying everything from naval mines to ASM, ground attack guided missiles, bombs of various sorts, capable of say firing potentially anti radar missiles, anti runway missiles, and the like giving it a lot of diversity of capability. While also being intended to be operated from rougher airfields in a potential WW where the aircraft could be forced to use anything from smaller airstrips to reinforced stretches of highway.
So the US goes with the Super F111 instead of the B1. The Tu22M like aircraft is smaller then a B1 so less theoretical ordinance but its still quite capable and the reduced cost of construction and operation result in significantly more being acquired then the B1a/B1B with roughly 250 being constructed instead of 100 of the B1Bs.
Even less likely is for say the USN to actually buy in and buy a force of say 24-36 (two to three 12 aircraft squadrons) bringing the constructed total up to roughly 275. The Naval version is specifically intended to act as a counter to support the USN's surface and submerged fleet against the ever growing Soviet surface fleet. The naval variant is still land based but focused more on Anti ship work (or anti enemy naval/air base work) carrying things like new cruise missiles, guided rockets, naval mines, cluster bombs, dumb bombs, anti runway weapons, incendiary, anti radar weapons and the like. So you might see the naval bombers say hitting the enemy's radars/SAMs, runways and mining the port entrances immediately before say carrier aircraft make a strike to try and destroy the fleet in port.
So basicaly no B1s, the F111 gets modified into something like the TU22 was turned into the TU 22M, the USAF and potentially navy buy a good deal more then B1s were built. The super F11s are intended from the start to be very versatile in weapons usage. This might save some wear and tear on the B52 fleet. And the FB111s probably get phased out or modified into F111s with the Super F111s taking over the FB111 role.