The BONE (not heard it called that before) is a very different aircraft designed for a very different mission, though that doesn't detract from its CAS capabilities.
I don't think anyone is suggesting that the USAF won't be able to do CAS without the A-10, I think the point is that they'll not be able to do it as well.
Which is basically my point. CAS is a
mission, not a
platform. Some platforms excel in some CAS mission scenarios and others in other mission scenarios. USAF is pretty unique in that it has multiple platforms to perform the various CAS missions (and so far, we haven't even touched on C-130 and other gunships and armed UAVs in the CAS role). And yeah, shooting a 30mm is cheap compared to shooting a Maverik missile. But JDAMS are pretty cheap too and very effective in the CAS role and getting more and more effective. And fielding and maintaining an entire fleet of A-10s just so you can shoot "cheap" bullets when you have many other CAS capable platforms may not be a cheap solution in the overall scheme of things.