The GAF will use the F-35 to replace the Tornado around 2025-2035. The new fighter will be to replace their Typhoon and the French Rafale arond 2035 onwards.
That leaves the UK to decide what they will use to replace their Typhoons, the planned next generation US fighter or join the Franco-German programme.
The present plan for the next USAF fighter is a long range Penetrator Counter Air designed to escort the B-21 bomber into contested airspace in the Pacific (China) theatre. Which may be unsuitable for the UK - or not available as with the F-22 it will replace.
As history shows,however, cooperation with the French means they want to be prime for the airframe... and the engine.... and the control software.... etc.... etc...