I am surprised that the Tranche 1 Typhoons have been scrapped already. Does that reflect high usage due to low fleet numbers, rapid obsolescence of the technologies or a lack of cash and personnel to keep them in service? Compared to some earlier airframes those lifespans seem short.
Cash.
The airframes had only used up about 60% of their life, BAe did offer to upgrade them but, from all reports, the cost wasn’t worth it for the remaining life. Reducing them to spares reduces the ongoing costs to keep the rest of the fleet running.
There was a lot of support just to keep them as is and use them just for the AD QRA role in the UK and make the rest of the fleet available for OOA ops, but the money wasn’t there in the budget.
Again, as stated, there was/is pressure to buy additional new aircraft, but they can’t even find the money to buy the planned additional F-35Bs and the F-35A buy seems designed to save just a handful of extra cash as they are marginally cheaper than the B.
The saving factor for GCAP/Tempest is that contracts have already been signed along with Italy and Japan and it would, presumably, now be more expensive to cancel than continue. One of the advantages gained by being in an international consortium as opposed to the disadvantages.
The dogfights in future won’t be about buying more Typhoons but about how the available cash is spent between buying tranches of F-35A/F-35B/Tempest and total fleet numbers.