All good questions. You basically nailed it on the head. Those planning to stay and those who believe they'll pass PMTA are likely going to speak it fairly loud. If not simply for the fact it proves they managed to somehow get through the PMTA process which I can assure you is stringent. Those not willing to stick around will probably stay quiet for fear they'll lose customers.
On the flip side, some companies we've got wind are going through PMTA are staying quiet about it. (These are the really big guys. There is no official step by step but they're using some more traditional methods to get a head start. They've got huge budgets) The main reason is that anyone who can obtain PMTA has a major marketing advantage, so, they really don't want to offer up any sort of support clues to the smaller guys on how to make it through the process. (The larger players). What this has really done is ensured big players, especially those backed by big tobacco obtain a de facto monopoly in the US. I've always had a feeling it'd likely go this way. Kill the competition through legality and regulation.
Companies like NJOY, Blue, etc are all very likely to move forward without much issue. They've been building up resources for years with huge supply lines. I'd imagine that some of the larger liquid companies who saved or invested their money are likely to stick around. But without knowing how much some of these guys made it's hard to say. For hardware companies like Kanger Tech & Aspire are planning to push through the PMTA process. Their biggest concern is that because they are Chinese based that the FDA won't work with them. Most however are eager, willing and financially capable of making it through all of this.
For us personally, we're not 100% sure at the moment. (Thus why there's a lot of focus on Vapor Talk Asia and Vapor Talk Europe, which is a shame because those are potential jobs forced away from here..) We've got our products already our for testing and we've started the pre application phase. We're still mulling some things through with our investors but Vapor Talk's Black Line alone could cost 6 million USD to push through PMTA - with no guarantee it'll pass. And it's only 5 flavors! the 6th being reserved for outside markets. (Prince of Jazz) If our application fails, we pay and repeat until the FDA gives us the greenlight. 3 runs could cost upwards of 18 million dollars. Incredible.
If you want to stay up to date on who is going and who is staying I'd suggest just staying on the forum. (ECF is another good source of info) I took a back seat role for a few years but these days I've hit the ground running and staying pretty well up to date. I'll start up video/podcasts shortly and will do my best to keep everyone here in the loop on whatever I managed to find out. Roger's in Beijing and usually keeps me up to speed on how little China is progressing with the FDA.