I think Milley is saying this because he knows there is a good Ukraine is going to lose.
If you look at our involvement since the start, there is a constant escalation of the weapons we send, and yet... Ukraine continues to not win. Stingers, then Javelins, M777s, HIMARS...etc. Everyone was going to turn the tide, but it hasn't worked.
Russia made some serious errors in the first months. Since then, not so much. Weighing the statements from West and East and trying to guess the truth somewhere between - and looking at maps - I'd say the Russians are making slow and steady progress.
I'm guessing this progress will continue even if Patriot missiles arrive. Patriots will help at first, then not, just as every other "game changer" has not.
It is also unclear how many NATO troops are actually on the ground helping. If Patriots start showing up quickly, either NATO troops are manning them, or NATO has been training Ukraine already for months.
In either case, it would mean that Russia's claim that they are basically fighting NATO is at least partially true. The way it looks now, Russia is slowly winning that war. Which is why the US keeps escalating.
Obama rightly said that we should not be doing this, because Russia will always have the escalatory advantage in Ukraine. I don't even particularly like Obama, but I have to give him credit where credit is due.