Justified or not, the gay elf cliché already exists in some people's minds. In my experience mostly immature homophobic people though. The kind of people who accuse someone as gay for playing an elf in the first place.
Zandir in drawn together is proof for that, because ALL the characters there are based on clichés. He simply wouldn't exist, if there weren't a cliché.
But I don't think that Fenris being the s/s LI would enforce the situation except for people who are seeing elves as effimate twinks already anyway, so there's nothing really to lose. Especially in the Dragon Age universe elves are very diverse. There are City elves, the Dalish, elves who belong to the Circle...Then vou have Zevran who considers himself more Antivian than anything else. Which is why he doesn't count as "typical gay elf" in my oppinion anyway. His bisexuality is by everyone in the game percieved as an antivian thing and not an elvish thing.
His flirtatiousness is also not depicted as an elvish thing but as something that comes with the rogue lifestyle. No part of his sexuality seems to be based on the fact that he is an elf, but of course you only know that when you actually play the game and get to know him. Same as finding out how deep he actually can be when he falls in love with your character and refuses to sleep with him/her for a while out of confusion. A lot of people seem to ignore that part and just see him as easy.
So, speculatively, you have an Antivian rogue and you have Fenris. A former slave warrior with issues and mysterious abilities. Ignoring the elf thing for a moment, it does make a potentially interesting LI with new obstacles in a romance to explore. If you wanted to have a character with that background in the Dragon Age world, what race would make more sense than an elf? But again, I don't see the race as the most prominent trait. It's more like it comes with being a slave than the other way round. Of course, there will be people who will only ever look at it from a very superficial level and probably brandmark it as a recurring cliché about elves, but should a writer concentrate more on trying to please the masses or tell the story they want to tell? IF Fenris turns out to be a s/s LI, he wouldn't be first and foremost another elf for me, but a character with an intresting backstory that provides massive obstacles for the romance. Which is good!
Jimmy Fury wrote...
I have to admit, all previous debates aside, that the Fenris obsession is fascinating to me. We know nothing about him. His description so far could apply just as easily to a complete sociopath as it does to the "guarded stoic" people have taken it as... All we know is that he was tortured for years, turned into a killing machine, and escaped.
Yet so many people are already so certain that he's this gentle shy romantic... It's just so weird to me.
This is basically a summary of a very popular theme in fanfiction. For some reason that I can't explain, lots of people seem to dig the idea of a romantic relationship in which one partner helps the other to overcome their horribly dark trauma from the past. Where there is no canon trauma, one would be made up for the fanfic. It's actually so frequent that it has become its own cliché or category in fanfiction, so it's probably not so surprising that some people are hoping for something like that and therefore projecting it into his character. The concept appeals.
Personally I am hoping for Fenris as a bi LI. I can't decide whether I'd prefer it to be a friendship or rivalry romance, both could be amazing. On the one hand there is the possibility of gently gaining his trust and friendship until that moment that someone described so beautifully, when he let's himself be touched for the first time. Never was chaste handholding so sweet.

On the other hand, I can easily picture him as a bit more agressive. Wall pinning was mentioned. I'd like that, and if he is indeed short tempered (I don't know if that is actually confirmed or not) there probably is potential for a rougher kind of relationship. BUT! I want to see Fenris do the pinning! After all, what's the easiest way to get around his aversion of being touched? Let him do the touching.

I would have loved Anders as an LI in Awakening.
When I heard about him being possessed by Justice I thought meh...But when I herad about the vengance twist I was like Hell yeah! THAT is interesting. But please not as a LI, because now I want the story focus on that and he probably has enough on his plate right now. There could be so much more exciting things going on now than a love story and I think a romance would steal the spotlight from that.
Justice was never motivated by anything but...justice. It will be similar now, so I can't imagine him being interested in romance at all. I assume that Anders is very busy trying to fight for his very existance and not getting taken over completely, don't see where he has the energy left for distractions like love. Poor guy, he only ever wanted his freedom and now he isn't free in his own body.
I used to dislike the idea of dwarf LIs, just because personally I don't like their body types and what I thought was their general character traits. But Varric seems so very awesome and different, I could warm to the idea. Consider me dwarf curious. I don't know if it's likely though. I'd prefer Fenris, all things considered. Simply because, based on what I think I know about the characters so far, Fenris has the most intriguing potential for a romance story.