The justification for Nero looking exactly like Dante in DMC4 was how that's just the way DMC characters looked and they were trying to stay with the general theme and artstyle of the series? 
 
So why's Dante completely different now?
 
Sure, this is another developer, but they claim that Capcom is also at hand to look over the thing. 
 
...
Those lying bastards
 
This makes me hope that the character is Joe Randomer who has Dante's memories implanted on him in a Jackson Lake from Doctor Who sort of way...

FUCK! I didn't know they were makin' another. Hell. Yes. Well, actually, I should disperse my excitement. I got this excited over DMC4 and the game definitely didn't live up to my expectations. 
As far as Nero goes, pshh, needless entry into the series. I kinda like his arm, though, and how they used it to incorporate the more trendy GoW-styled combat. 
 
Alright, just watched the trailer. This game looks incredible. I don't think I've been pumped for a game this much since MGS2.  And... interesting... looks like they wanna stick with the GoW stuff. 
 
And I don't really understand your complaints. I mean, I hope this is Dante. The game's just in a different style, is all. My only worry is that, since Ninja Theory is behind it, the game will be 4 hours long.

" He doesn't look completely different if you change his hair to white you'll see the resemblence. "

My theory, and I have stated this a few time,  is that it is 17 year old Dante or younger and his hair will gray out by the end and he will stop smoking by the end in a cheesy cutscene.

yah it's a reboot of the series, so they can change what they want.

Capcom's never had to justify a pallet swap before, why would they do one with Nero?

The best Devil May Cry game I've played is Bayonetta, closely followed by Devil May Cry 3. I want the Story to be inconsequential, campy and ridiculous and the gameplay to be hectic and thoroughly enjoyable. They are the ingrediants to a good DMC. DMC4 knew this (and so did the anime), but fucked up on the difficulty curve by dropping Dante in the deep end without any experience with his moveset and enemies that refused to acknowledge they'd been hit or ever die (think gladiator raptor men).
I'm not looking forward to it by any means because it seems like such a radical departure, but I'll give it a shake when the demo comes out.