Makoto Asada, the head producer for Cave's console ports, left a devastating message for all their worldwide fans on their development blog today. The message simply states:
A truly gut-wrenching blow to all of the shmup fans who believed that Cave making Mushihimesama Futari 1.5 a region-free title was a sign that they will continue to do this for their future titles(myself including). While Mr. Asada does leave a small gleam of hope to shine through with his last line; "for the time being", the entirety of his statement seems pretty ominous to me. Of course, this could all just be left open to overseas publishers to pick up their console ports to do their own localizations, much like Aksys is currently doing for Death Smiles.
In fact, the only reason I could even see Cave completely region-locking their future games is because they intend to properly have them released in other foreign markets. I can't imagine that region-freeing Mushihimesama Futari made them lose any money, quite the opposite actually, considering the pretty strong fanbase they have outside of Japan. Either way, if you're currently an owner of a J-360, I would hold onto the system for a little while longer. You have no idea what us shmup fans will have to endure through next!