I believe the deal will go through and ALDW can't crash ahead of it or folks like me would buy the future DK shares on the cheap by grabbing ALDW units before it ceases to trade. I see the 4 days of trading since the announcement has them in lock step now.
What will happen, imo, is as of January 1st those that get to put off gains and not wanting the low2% dividend from DK will sell ALDW and book those gains in 2018 effectively delaying uncle sam and having a year to seek returns with the money in higher yielding plays.