When SureFire first updated their website, I talked with them in their forum (now gone) & the M8 was going to be (at that stage atleast) the DL123A equivalent of the new M2000 rechargeable. I assume it'll have two rows of four batteries side by side. SureFire said that 500+ Lumens is about as much as technology allowed without melting the components etc (They said increasing the bulk of the flashlight would help reduce the heat, but SureFire wasn't into making big bulky flashlights).
I got the impression that SureFire was testing the waters with the M3, and taking a leap with the M6. I suppose it's all sales related. If there's demand (ie everybody emails them lots) maybe they'll make an M8. I hope they make the M2000 atleast!
I've been in San Marino (Italy), and they're really into BB Guns, and associated firearms selling them to anybody; even kids (which I'm against). I was very surprised to see a BB machinegun with a SureFire 9P and lasersight (not SureFire). They also had a 12ZM for £250 which was way overpriced.