This was only recently commented on the other day in another section, but it looks like the Reissue of Gen1 Sixshot is still coming in August, according to online store Kapow toys.

Apparently it will have special/expensive packaging, but that might just be the Asian release (as previous JP reissues & Masterpiece have had bonus items with their Asian/HK release). Or maybe there won't be a Japanese release at all, which might be why we haven't seen anything of it in recent JP Hobby magazines.