I think a popular non-D&D fantasy RPG, which might be called by some "traditional" is certainly possible.
I don't think the "first to market" BS really flies, frankly. I mean, people say that and keep saying precisely until it's NOT true any more. It happened with MMORPGs, big-time, for example, and it's happened in other fields and genres of RPG.
What does fly is marketing oomph. You're not going to get a sizeable market share without serious marketing, these days. So that really only leaves two possible companies to put out such a product - WotC and WW. Both of them have a degree of inherent "branding" from their name, and if one of them put out an entirely new, non-D&D FRPG, it would attract a LOT of interest from gamers.
With marketing, you might be able to make it appeal to current non-P&P RPGs, too, whether people who read fantasy, or people who game, but don't play P&P RPGs. I don't think, however, that trying to take a slice out of WotC's pie is the way to go about it. You need to do what WoW did, and to try to "grow the market", and appeal beyond the current gamers (something 4E, currently, fails to do due to the lack of an introductory product). Differentiation from D&D would be key, too.
I'm a little dubious about this term "traditional", though. I mean, wth is "traditional fantasy"? Is it Tolkien? Leiber? Howard? Moorcock? Le Guin? C.S. Lewis? Rowling, even? They're all venerable enough, and despite Rowling's protestations, she's pretty much trad in all her fantasy ideas (conservative even, hilariously). If we're talking about a game that could perhaps encompass all of those mentioned, and did not have D&D's focus on "ultra-magic" and it's many non-human PC races, then I think it could do well on the differentiation front.
If it was just another D&D-style Tolkien-rip-off with Elves, Dwarves, dungeons and dragons as typical places to go and things to kill and so on, then no, I don't think there's much room for that.
As for being a fantasy heartbreaker, well so's 4E, essentially. It's just a fantasy heartbreaker (and it's breaking a MEGATON of hearts RIGHT HERE guys, so no denying it) published by a very successful company, and that's what separates a typical "fantasy heartbreaker" from a successful fantasy RPG, imho.