I would agree with you on that point, but it is all down to whether the USAF could afford the 500 NGADs it all depends on the budget. I would really like to see 500 NGADs.
If the current status quo will become hot, and the Doomsday Clock moves a bit closer to 0, the Military-Industrial Complex will work wonders and deliver us more than 500 NGADs. All that to make the point clear that if someone will still bother to attack the US, then they're way past Deterrence now.
That being said, it could also be possible that they won't deliver 500 NGAD units or more in that situation, rather that they will show far more secretive projects and use them when the situation calls for it. That is, if they're willing to use such technologies themselves.