These stealth programs are so prohibitively expensive these days that I'd argue that they'll never see the light of day.
Look at what's actually making headway:
The US has the F-22 that's out of production and was essentially the product of unlimited cold war budgets.
The US and their partners have the F-35, which needs production numbers of 1000+ to get per unit costs to under $100Million each
The US has the B-2 that is out of production, is a cold war unlimited budget product, and didn't hit 50 actual operational frames.
The US has the B-21 that is reusing much of the internal systems of the F-35, rehashing a lot of the aerodynamics of the B-2, and is reusing the F-35 powerplants and will still likely be north of $250Million each on the low side.
Russia has the SU-57 which is arguably not fully stealth, they're only going to make 12, have no clear plans on how they will ever afford more, and lost their only international partner on it due to spiraling costs.
China has several platforms under development that have various degrees of stealth. The only reason that they can afford them is that they are essentially fully government funded by the most populous nation on earth that has an essentially bottomless checkbook and still has been found to be getting a lot of their R&D through corporate espionage. Even with all that, they are still struggling to build turbofan engines that are as good as Russia's best from 10+ years ago.
There are a handfull of other countries attempting to develop something. Japan is trying to get with LM to get a hybrid of the F-22 and F-35 of the ground, but almost had cardiac arrest when they saw the sticker price on that one. They tried their own, proved that it could fly, and then realized how expensive it would be to go any farther and just parked it. Turkey started and stopped a program that would have involved Bae.
The UK and Italy don't have a prayer in getting anything past a wind tunnel or subscale flyable prototype without a lot more countries coming on board. France and Germany are in the same situation, heck, Germany can't even keep their own existing military operational and France can barely find anyone to buy the Rafale as it is. IF, and ONLY IF, Saab, Airbus, Dasault and Bae could find it within their hearts to get together and develop two planes that share everything under the skin possible, but have their own airframes, they could come up with a pan european family of fighters that can perform Air superiority and multi-role strike in a gen 5+ environment. They could even have interchangeable nose modules that allow them to be optionally manned and optimized for each role. And, even with that level of cooperation, the final product is still just a pipedream as they would still struggle to fund it.
Going forward, China will eventually run away with military tech. They have the deep pockets, the population, the resources, and the will to start, fund, and complete these programs. The US is running into its own problems funding their existing military and the uber expensive future programs are going to drain them dry in the long run.
Ever thought that experience with these partners in the 80's and 90's might have made BAE leery? France demanded 39% of workshare in the 80's for a new European aircraft, as well as insisting also on not only a smaller aircraft but French engines optimised for that size of aircraft.
The reason that the ACA mock-up in 1982 had some changes to the actual EAP that flew in 1986, was that Germany was to design/build the EAP's rear fuselage, they pulled out so a modified Tornado rear fuselage and single fin was substituted.
Germany did stay with the EFA programme, then they wanted out in 1992, claiming it was too expensive, eventually settling on a faux 'cheaper' version (it wasn't) that just brought delays and yes, extra costs.
In recent years however, the French aircraft has won export orders, is in the running in several competitions, I am sure they would have preferred them sooner but the facts remain that they have gained them.
They even, in the end, at least extracted a 36 aircraft order from India, after that nightmare of a procurement process.
Typhoon is still selling, looks to be in production until 2025, few on here thought that not so long ago.
As for the German AF, they did agree to raise spending in 2014, not as fast as other NATO allies would have liked but the direction of travel is clear after years of going the other way. They don't only have an AF to consider here either.
As I mentioned before, Japan has had some reason (F-22 refusal) and the conduct of the current US President, to not be quite so reliant on the US. Their X-2 Technology Demonstrator ended it's flying late last year, this was a program started to look at what it would take to develop a F-3 aircraft, either wholly Japanese - not that likely, or as a partner in a new fighter program - rather more likely.
They do have 42 F-35's on order and could likely expand that number, however so do both the UK and Italy.
It would be better if this proposal does become a pan European one, however history suggests it might not do.
As mentioned before, this project has been in the works since 2015, $2 Billion set aside from various UK departments, MoD included, was not done just to make headlines at one airshow this year.
A lot more than that will be needed to go further over the next two decades and as also stated, it won't be a UK only effort.
That went out in the 1960's.