John,
I agree to both 1 and 2. Operators need to spend money on new technology.
However, the F-35 brings two unique capabilities to the party: STOVL, and a degree of stealth that (I think most sources agree) is between that of a Rafale or Advanced Super Hornet and an F-22.
I will even cede that (probably not in Block 3 but possibly in Block 5 by 2024) it will have better sensor-fusion and networking smarts that anything in service today. However, that's something that is retrofittable.
The question "are STOVL and F-35 stealth worth the money?" was never supposed to be relevant, because the F-35 was promised to be cheaper to buy and operate than anything else. Costs are now crucial, because the price of F-35 is cutting force numbers.
So as an operator, I ask "do I want STOVL and how much is it worth?" and "I probably want to exploit stealth - but am I better off with F-35, or with Rafale/ASH levels + good EW + a few very stealthy UCAVs?"
Hypothetically say that we decide to cancel the F-35 program, would there be a mix of 4.5 and 5th gen aircraft that could work.
If say we can restart the production of F-22s, and double the # of Raptors in service, that should ameliorate some of the issues of not having stealth LWF and medium range interdiction. Along with purchasing more 4.5 G type aircraft (Superhornet, F-15E, Rafale, etc), seems should be sufficient for US and allies until 2040 or so. Does that sound like a workable solution?