Sounds to me like a lot of brokers are trying to keep the anxiety level of their own traders down by telling them that 'everything will be ok.' This makes sense to me, and I'd probably try to do the same thing in their shoes.
However, after reading a copy of the letter from one brokerage firm, as well as reading the article on Green's website, it seems clear to me:
In order to trade prop the following conditions have to be met (per the SEC/NASD):
1) Licensed S7 and S55
2) No deposit/assurance bond/any capital of the trader can be with the firm. Trader needs to trade firm capital
3) There has to be a sharing of profit between the firm and the trader (100% payouts do not pass the test)
=> Assuming this is true (and it certainly sounds that way from everything I have seen), then the arrangement at SwiftTrade would appear to be the only prop model that I'm aware of that meets these conditions. Per Green's article, this policy may be phased in over the course of a year, as each firm goes through their routine auditing process with the regulators.
In the short run, we can only speculate. However, I think traders need to begin planning for contingencies now, even if their firms are confidently telling them that they 'have no problem' to worry about. Nobody is going to look out for your interests as well as you should do yourself.