I read a Quoro post that made me reconsider some of these CAS arguments.
The F-35 is not going to try to do what the A-10 does, it is going to go about things in its own way.
The modern era has given us forward observers in greater numbers than ever before so the F-35 can stay upstairs and hidden and pop off a small missile or small diameter bomb to plink something that is being designated while the pilot sits surrounded by sensors and inputs to know where they need to be. The F-35 is also going to be able to get to where it is needed to provide support a lot faster than an A-10, especially if the A-10 had to go around something that would be a threat like a SAM site.
With Air-to-Surface Missiles with a longer range and great reliability but small (ish) size, we don't need the A-10's 30mm monster cannon and the lack of sensors or pilot aids hurts the A-10's ability to actually provide support when, as above, it eventually gets there.
If this was the 1980s and the Soviet Shock Armies start rolling across the border into West Germany then I'd love to have A-10s around but these days... I'd go with F-35s which can do the same thing in terms of hurting the person being nasty to you while training aircraft (Tucano, BAe Hawk etc) or drones can be adapted for lower intensity or threat work or if you are worried about losses.
Finally, the F-35 also offers far better strike and interdiction capability to kill the enemy's bridges, logistics etc as well.
Is the F-35 perfect - far from it. Is the A-10 golden - not really.
Is the F-35 viable for close air support? not really. when it's there, sure, (anything that can drop a bomb is-once.) but it won't be there very often, nor for very long. having CAS available for 2 minutes out of every hour (flight time from refuel to front and back) you need a lot more of them to maintain coverage on ground units, then we get to payload. The 35 has less payload than an F-5E. (not that it matters when you can't stick around.)
the '35 is a first-strike fighter, it's an air superiority fighter, and that's where you hit the wall. USAF doesn't like doing air-to-mud in a combat situation and spending the price of an abrams-each time-to blow up one or two insurgents is pretty damn wasteful in munitions-and that's what you end up spending, because the F-35 can't survive air support as a mission-it can only do the stand-off mission the F-15E already does for less, in an environment where enemy ADA has already been suppressed into nonexistence. (See, you LOSE all that nifty stealth advantage if you give it enough warload to actually carry more than a very small number of bombs.)
and it lacks fuel range, which in turn means linger time, meaning it's unavailable more often than even the supersonic jets we already have in service, and available LESS OFTEN for calls from troops that 'found' that concentration of enemy.
It's more susceptible to random damage as well as aimed damage-heck, it's more suscepible to damage PERIOD. (and again, damage eliminates that stealth option, but in this case it's harder to keep in the air!)
"in it's own way" means they'll assign it the mission-and it won't execute that mission except on paper.
Smart munitions are insanely, absurdly expensive items. you CAN buy a main battle tank for the price of some of the ones we have in inventory-difference being, an MBT will be usefl for several conflicts, and a smart bomb is useful in only one engagement in one conflict (per unit). The whole reason the Navy's looking at gun-based systems and the army's repeatedly putting new howitzer designs up, is that the per-shot cost is so MUCH less than buying guided missiles or smart bombs.
really, really so much less, you wouldn't believe the price difference unless you've seen the numbers congress sees.
