Forgive the intrusion but this is my first posting onto this forum. For what its worth I believe that the UK does have other options, at least for the RAF.
The UK other option is to replace the JSF with the Grippen. I think we have a 40% share in the aircraft anyway so costwise that would be a good option. Its a very capable plane from a manufacturer who has an excellent track record. As an RAF replacement for the JSF it has a lot going for it. The Grippen has some overseas sales to its credit, and you can be sure that the RAF would get a good deal should they go that way.
The problem is the Fleet Air Arm, at first glance the Rafale is almost the only option, note almost. Its available, will not need, much if any development and the carriers are designed for it. However the French do not have a terrific reputation for swapping technology and we may well have a similar problem with the JSF.
So we are left with having to develop a naval version of another plane.
The cost of developing a Naval Typhoon and the delay it would cause is such that I believe that its a non starter. Would anyone bet on less than 7 years?
The cost of developing a Naval Grippen is probably less than the Typhoon. Its designed for rough surfaces and it probably will not need as much beefing up as a Typhoon. Its versatile and can carry out the air to air and attack missions, plus we will not have to rely on other countries to assist with the development. The last point is often overlooked. The overheads of dealing with other countries are significant particually if you need their input into designing and building new parts.
I would bite the bullet, go for the Grippen and take control of our own destiny.
Remember that if other countries see the UK, the USA's closest friend walk away from the JSF after spending 2 billion on it because we do not trust the USA to give us the support we need. They are likely to say if the UK doesnt trust the USA, why should we?