I can already see that these pairings aren't going to last, and for numerous reasons. For starters, even if we didn't take into account Ian's "no stready relationships for Sonic" statement, in order for Sonic/Amy to preservere, it would require Sally to be in a more long-term relationship with Khan-- which isn't going to happen because fans are going to object to this whether they're SonSal fans or not. Why?
Simple. One, of all characters, its Khan being paired with Sally, a character that's been generally disliked amongst the fans. Two, how Ian writes him. Khan is so annoyingly wangst-ridden, mopey, and tempermental that, it makes Shadow the Hedgehog look comparitively normal. Put all this in a blender and add in the fact that he and Sally develop a relationship in an abnormally short period of time and you have discord coming in from both sides. Because if you were a fan of SonSal, your obviously not going to be bought in by some guy you probably didn't even like in the first place, who all of a sudden comes in and sweeps Sally off her feet with little development.
And even if you didn't like Sally or the SonSal relationship, and wanted her out of the way and with someone else, to have her date Khan would mean that you'd have to stomach not only her but more of both of them, more than you already have to. Not to mention you'd then have to deal with the incessant moping that would normally be in character for Sonic upon realizing that they're 'official'.
If Ian were honestly sincere about Sally being with someone else, don't you think he would have put more thought into who the guy was? That he would have chosen someone that fans would have approved of more? Like say, Shadow for example, or Knuckles? And even if that weren't the case, don't you think he would have invested more time into the development of these two characters like he did with SonSal instead of trying to rush them together? After all, Khan "isn't very popular", amirite?
Oh yeah, and before someone says it, I AM aware that he's Ian's little "pet project", or so he says he is on his board, but even if that were true, keep in mind, that that came BEFORE the idea to pair him with Sally. Just because Ian's supposedly writing him with the intent to be liked more as a character (and failing), doesn't mean Khan's being written with the assumption to actually win against Sonic for Sally's affections in the long run. Ian may say who Sally and Sonic are with is "up to the fans", but how the heck is this much of a choice? Oh sure, Sonic's picking up Amy on the rebound, but SonAmy's development all relies on Sally being in a relationship that won't last. He picks a guy for her that wasn't very popular with the fans to begin with, then rushes them into a relationship and expects the fans to feel as though they have a choice? This Sally/Khan pairing feels as though its being written with the intention to fail.
Sonic will eventually reconcille with Sally, Amy will return to being a backburner love interest and in the end, Ian will point the finger to the fans and argue that "this is what they wanted". Psh, yeah right. This reeks of yet another PR stunt, and I am not amused. He's just wasting our time with this, using his pretentiousness as some attempted vehichle for suspense when we already know what he wants to do with this love square, anyway.