Commenter Lou G stated that the grounding of the F-35 is no big deal.
I beg to differ.
If the F-35 fan boys are successful (and I don't believe they will be) then you can look to a future where the USMC is flying only F-35s. If they're grounded then that means that if the balloon goes up we won't have fast mover air support.
The same will apply to the USAF. The majority of their fighters will be F-35 if the plan carries the day.
A grounding for safety concerns can effectively cripple at least 2/3rds of the available fighters available to a future USAF/USMC/USN.
That is unacceptable.
This points out the need to have proven airframes in service for the foreseeable future. This is why we need the Super Hornet in USMC colors!