But then again I'm thinking maybe we will NOT encounter the Warden because they'd have to explain why the LI isn't there (since Zevran won't be returning and he's a potential LI).
Or well, I guess it would just interfere with my headcanon
That when the Warden and Hawke disappear, their LIs disappear with them.
But obviously that is not the case, since Alistair and Leliana are still around and have no idea (presumably) where their lover is. (Can't count Morrigan b/c who knows what she knows).
Yuck I've talked myself into believing this game will disregard the LI completely.
Morrigan's Ring would be an interesting factor in this... if a male Warden has it, Morrigan knows where they are for sure. One of mine does have it, but his relationship with Morrigan is... sour. I'm curious to see what comes of it, if anything.
My headcanon is that Alistair has my Amell's phylactery, but his position as king means he can't just go gallivanting off on a rescue mission, as much as he'd like to. 
As for my Hawkes' love interests, I'd hope they would be searching for her... though Sebastian has the same excuse of royalty as Alistair does.