Diamondback has simple looking trains, but is one of the complicated ones to rebuild. It'll be there.....there are still 2 weeks until it's needed to be there for opening weekend. It doesn't take all that long for a train to be commissioned for use once past it's opening season.
I highly doubt that they will use the 3rd train as a rehab during the season. Diamondback is a people eater and utilizes all 3 trains well, no matter how many enthusiasts claim it stacks, ruins capacity, etc. The general public doesn't see that or care that it "stacks" and often hasn't. It really depends on the crew each day. The numbers for RPH are generally higher than many think.
I highly doubt there will be a path from Slaughterhouse to Diamondback's Hammerhead turn to the midway by the train.
Directly under the hammerhead there is a drop off....it's not as flat as some may assume. I'll never forget during training my supervisors took us out there and told us to make sure we didn't get too far out from under the track, especially at night be cause the land becomes incredibly steep. When I got to the point where I was close enough to be safe, sure enough, it was steep.
We've also got to look at the area from the hammerhead to the train area. It's definitely not flat and is used for access roads. There are several lock out areas around there for low zones. Unless they would smooth out that land, place bigger fences to prevent folks from getting close to the lockout areas, it's not viable.