Hey Ron. You know, I've often wondered the same things myself. The law hasn't been put into place yet, and actually has only relatively recently been recommended, so it is likely to take quite a while before anything happens. It is also equally likely that nothing will happen because of it. Lawmakers aren't stupid (ok ok, most of them), and aside from Southern FL, Southern CA, and maybe Southern TX (doubtful though) no Boiga species could even hope to gain a foothold. I'd say even So. CA would be pushing it, as the climate is too arid. At best, Miami might have to worry about a "plaque" of mangroves, or blanding's, etc etc at some point, but don't they already worry about troops of monkeys around Miami airport and the whispers of a "colony of forest cobras" also in that same general area? To me that doesn't seem like it should bother them too much, lol. But no, I don't believe any of the Boiga species pose any sort of potential harm to the vast, vast majority of the continental US, as afterall these species are tropical and must feed all year round. They haven't evolved with a dormancy period like our native snakes. I think this is just one more way to try to inhibit our keeping abilities.
Now as far as the proposed law's effects on people who already keep them, I don't think they can do anything. Besides the fact that there is no national database of Boiga keepers, it would just be too difficult for them to gather up all the stray animals around the country. I'm sure you'd be allowed to continue to keep the snakes you already have, however the problem comes into play with selling offspring or buyer more captive stock. Unless done under the table (i.e. illegally) it would probably be difficult. But anyway, all these are just speculations on a law that is likely not to pass. Be ready for it if it does though. Don't sit idly by and watch yet another restriction be placed on your right to keep these animals when all the pit bull keepers in America enjoy the right of letting their dogs bite, maul, and even kill people occasionally without restriction.