Using only one console, 8 players could maybe be possible. Half the players could use gamecube controllers and half could use Wiimotes with anolog shells if it were using only one console.
Although I'm not sure if this could work, as the Wii may not recognise the 8 controllers separatly, and only recognise 4 controllers, even when using all the Wiimotes and GC controller ports.
Or they could release a gamecube controller multitap used on the GC controller ports on the side of the Wii, if that could work, as SSBB is most likely going to be primarily played by GC controllers, as the anolog wiimote attachment looks somewhat uncomfortable, and they say they don't see much use of the motion sensory in the wiimote. But then again, the Wii may not be able to process 8 controllers, as it would normally not need to, as few games would use it, because most multiplayer games divide up the screen, and a screen split into eight is ridiculous.
Now then, with online play, it's definatly possible, even if it would probably be laggy.
BUT, reasonablitywise, No. Not in most people's opinions.
But yes in mine. (no, I don't form alliances, I keep to the free for all thing going and smash whoever. Also, the best three opponents I have in real life teamed together (freindly fire off) cannot beat me without other advandages.)
2 is okay, you and a freind. personal.
3 is good, multiple targets, but not rediculous.
4 is crazy fun, beginners start to get overwhelmed even just amongst themselves.
5 would be getting insane
6 would be on the verge of chaos.
7 would be chaos.
8 would be absolute madness.
I know someone who refuses to play 3 player matches, and is actually quite good.
However, when I think for myself, a limit of eight is perfect. 6-4 would be my ideal amount of opponents, but I'd want to have the option to try 7 or 8 now and then. 9 and above is too much for even the best of us, not really ideal for anyone, even the best melee fighters (melee as in many people)
Now, how well would this fit in the SSB series? Rather.
Firstly, a good portion of thought of SSB is "insane fights between nintendo characters."
To add to this insanity, more fighters would be good.
Secondly, the title is super smash brothers brawl. A brawl is concidered a loud and noisy fight. More players, more noisy.
Thirdly, Brawl also means a party. (a noisy one to be specific) 4 people is NOT a party. It's inviting some freinds over. 6 is harld one. 8 would be one.
On the contrary, it doesn't quite fit the game, because it's not ment as a small scaled war. It's a good deal more personal, because you're usually within 7 feet of the person, and also know them.
And, past smashs have involved stratagy. 8 people crammed onto battlefeild is button mashing or jumping back onto stage, no stratagy.
However, I think it's most likely there will be 4 player limit per console, and 6 player limit per wi fi match. Maybe just 4 in wi fi. Maybe a whole 8 in wi fi. 6 just seemed a good comprimise to me. Also, I would imagine a limit of 4 Wii consoles being used in one match, as six would cause unbarable lag.
In conclusion, I say they should have optionally up to 8 players in a wi fi match, and in a one console match if possible.
If you don't like the utter madness, or the lag, or the idea in general, just don't play with 8 players.
(If you read through all of this, I am rather surprised, and I apoligise, but I felt I should explain my opinion in detail.)
-edit-
About those visors, that would change the game completely, if in first person veiw. Hardly a bit of Super smash left.... and it would still change it even if the camera angles were varied per person, because that would ruin the fun of the projectiles, blind aiming and no warning is no good.
Maybe as a minigame? Because if the whole game uses the visor, in first person veiw, that would RUIN it in my honest opinion. Sure, it could be excellent fun, but it simply would not be Super smash bros anymore.
but for other games, I could see that put to good use, with the screen not needing spliting.