As I envision it, when you make a human character in GW2 you would first choose your ancestry. Where do you trace your blood? This might afford you some small bonus associated with that racial stock. Nothing earth shattering.
Next, from a pool of characters defined by your ancestry, you'd select one Revered Ancestor, someone from whom your character is directly descended. This Revered Ancestors could be drawn from the cast of GW1. Maybe Mehnlo is your grandfather, and so you've inherited his sex appeal. Or maybe your new Krytan-stock ranger inherited Zho's (single) eye for accuracy. In any case, whatever character you choose will afford you some specific benefit associated with the Revered Ancestor in question.
Here's more or less how I'd do it. Each Revered Ancestor (henceforth abbreviated as RA) has five traits, each one equating to some benefit or bonus. As a descendant of this Ancestor, you can select TWO traits to define yourself. So maybe Koss has the traits (and I'm intentionally glossing over what these might actually DO, by the way) Brute, Charming, Connected, Daring, and Relentless. Maybe you envision your new Kournan-stock character as a swashbuckler, so you select Koss as your ancestor and take Charming and Daring. Simple.
Obviously some people will want to make their human GW2 characters explicitly related to their GW1 characters. This too can be arranged. Once the two accounts are linked your GW1 characters become candidates for Revered Ancestor. Which traits he or she offers as an RA depends on his or her class, titles, and recorded accomplishments. Unlike NPC RAs, player-made characters can offer more than five traits to choose from, but keep in mind that these traits are not unique. They can each be had by picking an appropriate NPC RA.
So, using your own GW1 character as a RA does NOT give you better traits, but rather, a better selection of traits. There might not be an NPC RA that offers both Brute and Clever, but your GW1 character might be able to offer both together. Ah, but maybe that one NPC RA offers Indomitable, a trait you really want, bunched with some other traits you're not as interested in. And maybe offering the Indomitable trait requires your GW1 character to have earned the title "My Apartment Smells of Rich Mahogany." Yikes. Suddenly there's a good argument for taking an NPC RA instead, even if it means having a sub-optimal second trait.
Does this make sense? Anyone else think this would be kind of cool? I'm sure it doesn't need to be as complicated as I'm making it out to be.

Unmaker
Edit: Allow me to clarify a few of my ideas. Firstly, understand that I wouldn't want these traits to be too powerful. I imagine them as merely handy, being limited in scope and/or situational. Maybe the Hard-headed trait means your character is less likely to be stunned or dazed. Useful? Certainly - but only under the appropriate circumstances. Also, to be clear, I don't intend these traits to serve as a replacement for a class system. In fact, while we're on the subject of class, traits shouldn't exist that are only useful to one class. Even the Brute trait, for example, should also somehow benefit a spellcaster. Granted, some class-trait combos will be more useful than others, but no trait should be married to a single class.
As I see it, the other races already have their traits as defined by their race. Norns are strong. Asura are smart. Maybe the other races have stronger, but fewer traits. Or maybe they have more traits, but (since they're not human) don't get to choose what those traits are. The advantage of playing a human (in this proposal) is that you have a greater variety of trait combinations to choose from. Anyway, that was sort of my thinking.