In Boyd Gaming's Call, they said that Echelon would remain dormant for three to five years, but they wouldn't take down the construction already started: "We anticipate using or incorporating the structure that's already in place into the new project."
I don't know the cost of clearing the land compared to maintaining the construction hulk, but this is obviously detrimental to The Strip. Further, when the market recovers, it doesn't seem likely that Boyd would follow its original vision for the development.
Boyd should be a good citizen and remove the skeletons. We may see how much influence Steve Wynn has on the subject: "When told that Boyd wasn't going to do anything with Echelon until the next presidential election, Wynn became somewhat incredulous. He wants to see Echelon's unfinished steel structure disappear as much as he wants to see the Obama administration vacate the White House."