The 15-month delays, plus the change requiring CLEO signatures for trusts, are absolutely going to kill this market. I just don't see people tying up $20,000+ for a machine gun under those conditions. And suppressors and SBR's aren't going to be commercially viable.
Lessened demand is going to mean lessened prices. Simple laws of economics.
On the other hand, prices of semiautomatic clones of machine guns (such as OOW's M1918A3 BAR) are going to go up. Even non-firing guns built on 80% receivers are going to go up.
And, ultimately, there's going to be an uptick in illegal guns. After all, the NFA, as administered until recently, was a sort of legal safety valve for people wanting these items. If that door is shut, well..... we have Prohibition as an example.
I have no doubt that the delays and the other changes in the way NFA rules work reflect antigun Administration policy. They're targeting what they perceive to be the "low hanging fruit" of the gun world. But in the long run this shows poor judgement.