Yeah I suspect the last track will stay out until access isn’t required - after most the the theming
The ride needs to complete so many hundreds if not thousands of hours worth of testing before
ADIPS and other authoritative bodies will sign it off as safe for people to ride. They will want the ride hardware completed ASAP so that this testing can begin. Ideally with theming and the landscaping being built in between and in tandem with the testing. I suspect theming won't be finished until close to the opening date, therefor leaving a track piece out would mean they would potentially miss the date due to the required testing.
For context, Nemesis at Alton Towers, while not brand new in the traditional sense, but brand new in the sense of 90% of the track replaced, new trains, control system and breaking technology (enough to warrent new certification basically) has been running non stop all day every day recently and it will continue to do so until every possible operating combination, potential fault and everything in between has been tested many times.
Draytons new coaster will probably make this testing process more complex than Nemesis with it's traditional layout, due to a much higher variation of things that need to be tested with switch tracks and what not. So getting the hardware up and running will be a big priority right now I would have thought. I guess if leaving track out was needed for access in the short term, they can complete the electrical side of the installation, then when that is ready the track can be put into place within an hour or so. But getting them trains going around that track will almost certainly be the number one priority right now.
This ride looks great, very excited to see how it all pans out. My 9 year old son is excited. This will be a big but not intimidating coaster for him, much better than the two other offerings he could do before withTroublesome Trucks and Accelerator. A few years off getting him to have the courage to ride Shockwave I think.
Passes run out towards the end of May. Hopefully it will be open by then but I've already made the decision that we will be renewing for the third year in a row. So no biggie if it is not. But I suspect they may aim for the easter holidays to get this open, it's usually a busy time for many themeparks, Drayton being no exception. So I suspect they will not only want the extra park capacity a major ride gives in soaking up crowds, but will want to capitalise on what is a busy period with their shiny and rather excellent looking rollercoaster.