It goes without saying that the chances of an early NA release, conceivably as early as June, just skyrocketed. Before today I was confidently expecting this game to land in October (the Bayonetta 2 slot, sliding neatly between Mario Maker and Star Fox), but if it arrives much earlier I do wonder what will take its place. It would be unfortunate for Yoshi to be bumped back that far in NA and for no significant short-notice announcements at E3 (although I still expect at least one Captain Toad-sized surprise), but in any case, I'd rather have Xenoblade show up sooner rather than later. If it comes out in June it will have practically no competition for my attention all summer.
The pessimistic scenario, release-wise, is that in the absence of Zelda this is being pushed as such a big game that we are set to see it promoted in this Direct, then again at E3, then again in a second Direct closer to release. The only precedent for this is Smash, and this just isn't Smash; people aren't salivating over a trickle of character announcements such that every promotional effort is by itself an event. So unless tomorrow's Direct is merely a first look at the English localization to pre-empt the JP release, things are looking up. The biggest argument against expecting an imminent release is that it wasn't even remotely hinted at in the April Direct as something we should expect in the coming season. If they knew they were on target to get the game out the door soon, why wouldn't this have been mentioned then?
But we'll see soon enough how close they are. We have yet to see anything of this game with either English voices or finished English text, and if either of them fail to show up tomorrow we should not expect a release date either. Remember that when the Hyrule Warriors and Bayonetta 2 Directs appeared with a two-month lead time that review builds were pretty much in the can and ready to send out. I've seen nothing to suggest X is that far along, but then again, we haven't seen it promoted in NA since what, November?
One item to look out for, if we finally see the English text (as we should), will be how the JP terminology carries over into the localization, be it the Dolls or something more obviously due for replacement like "Huge Succeeded" ("Shine Get!"). Mostly, however, I will be watching for a release date like the rest of you.