I dodged saying this yesterday, but I'll try it now:
If the out-of-state restriction is going to be gone by April 15th, I think we'll know on April 1st.
I would be very surprised if the state would just suddenly remove it on a moment's notice, knowing the kind of immediate overwhelming impact that decision would have. If it's like how it's (seemingly) done elsewhere, it'll be an announcement that the advisory will be expiring "as of" a certain date, such as the end of a given month.
My suspicion is that
Legoland is just trying to delay having to deal with out-of-state delays or cancellations. Almost like a hail mary, in case the state for some reason changes their mind. They've been a little flat-footed thus far, and I think they're just trying to give themselves a little more time to prepare for that.
If it's really possible that the state won't implement that restriction - Disney would likely be as aware of that as Legoland, which would give them reason to delay as well.
But I'm still really, really skeptical that the state will do away with the restriction quickly. Things are looking really, really good right now, but it's still a while away from where I think they'll want to be willing to throw the doors open.
I can't shake the feeling that the advisory is based on the same metrics that the tiers are. That's why I would be surprised if they separate the two. I still expect that they'll keep the advisory (and the restriction) until the overwhelming part of the state is in the as-yet unannounced Green tier. They've said that they're preparing that tier - and I think we'll know better once they implement it (assuming they do).
Btw - I've said this before, but it's true: I'm a pessimist only because if I'm wrong, it's usually good news. (Getting the best is even better if you're expecting the worst.)
But since predictions are fun, I'll throw this out there:
I think Disney will make an announcement sometime around/after the 1st, once the new policies are officially in place. Tickets and hotels will come later - ie, maybe April 12th or 13th.
If they do decide to give "priority" to hotels, I could see them opening hotel reservations early, maybe a week prior to tickets being open to the general public, and giving them first shot at park reservations. (That'd also give them a "soft opening" for the park reservation system.)