See, here's the issue I take with the new protagonist being N7...
Shepard was not a static character. We all had our own, they made different choices, were different classes, sexes, and even looked differently from one another. However, the one thing identifying factor they all had in common was the N7 logo. Sure, we are told about other N7s, and Vega even gets a tattoo of the insignia, but throughout the campaign, N7 was strictly Shepard's identifying mark. On his or her armor, in the head's up display at the bottom of the screen, N7 meant Shepard. Even on Vega, the logo in a way symbolizes Shepard's relationship with Vega, with Vega looking up to the Commander. Sure, there are other N7s out there, and it has a very defined meaning in-universe as Military Vocational Code, however, to us, the players, we do, and are meant to, associate it with Shepard. Hell, the only only character in the single player series we ever see wearing actual N7 armor is Legion, and even THAT was once Shepard's armor.
Now, we've been told numerous times that Shepard's story is, for better or worse, over with, yes? His trilogy is done, buried, and we're moving on. Alright, that's all well and good, and personally, rather welcome.
But then we're told that the new character is going to be an N7.
If you think about it, suddenly there is a bit of a slant to things here and a few wires are getting crossed, even if it's just on a subconscious level. We are told we are moving on from Shepard, yet our new protagonist is going to be wearing what has come to be known as Shepard's sole identifying logo? We are trying to move on from Shepard, and yet by doing this, players are going to be reminded whenever they see their new protagonist wearing this armor that it is, in fact, not-Shepard. We are supposed to be moving on, but how can we when the new protagonist is going to constantly be measured up to what he is labeled as, but is in fact not?
Now I know what some of you are thinking, right? You're thinking that it's kind of a silly thing to get all bent out of shape over, I mean, there ARE other N7s out there, even if we don't see them, what's the harm in playing a new character wearing a symbol that the fans recognize as being as much their own as it is of their playable protagonist? To that, I posit this. Imagine if this new character was going to be a Spectre, something else Shepard was defined for through much of the series, would that also be a problem? I don't think so. Shepard was a Spectre, sure, but he wasn't THE Spectre. We met plenty of Spectres throughout the series. Nihlus, Saren, Bau, and Vasir. Being a Spectre was a quality of Shepard's, but it wasn't his identity.
The N7 symbol, however, is a different story. It IS Shepard's sole canon identifying mark, and whenever it isn't seen on him, it IS seen by something that is related to him, Multi-Player not withstanding. Anything you slap N7 on is instantly going to associate it with Shepard. Even if it's on a subconscious level, it's still going to be there.
And so slapping Shepard's symbol on a new character we are specifically trying to divorce from Shepard is a bit of a problem. I mean, if we're going to be playing an N7 again, why can't we just play as Shepard (Yes, because he's dead in two out of the three endings, I know, but you see my point)? I mean, we're going to be running around in a Mako like Shepard, we're going to be shooting stuff like Shepard, and now we're going to wearing Shepard's mark on our chests, right?
The point I'm trying to make is this: I'm all for a new protagonist and new adventures. I'm excited for it, even. But you can't tell me you want to make a new game that isn't about Shepard then make a character that might as well BE Shepard as the protagonist and honestly expect me to think you don't see why there might be some dissonance there.
If we're going to be playing a new character, give him a new insignia or something. Make him or her something other than another jar head. I mean, I think it's cool you're going for less of a soldier appearance and more for an explorer/astronaut vibe, I think that's great! But it kind of doesn't work when you make the character another Special Forces Marine who for all intents and purposes looks might as well be the exact same character we started the franchise as.
Maybe I'll be wrong in the end and this new character will have enough going for him that he is his own character separate from Shep. But I'm going to be very blunt and just come out and say it... some people are going to be looking at that N7 on his chest and forever measuring him up to Shepard even more than they were bound to do to start, especially given Shepard's unceremonious and often contested end at the end of 3.
It's too early to tell anything concrete, and that's alright, it's early still and I gather that Bioware is just feeling things out. On that note, however, I will simply conclude by saying seeing that we'll play another N7 human and what that insinuates leaves me feeling a sense of trepidation regarding the identity of the new protagonist and whatever story is going to be told through him.