@Pablo_Valente The only thing I can think of is that they want to make sure it's working as best as possible before committing to a ship date.
If they pick a ship date, and a Preview tester discovers a critical bug in the software, I wouldn't necessarily want that on my door without the software update applied. I'm sure that it can be fixed, but would I want to risk the chance of running in to that?
For myself, I say no.
The crowdfunded design had this problem. There was not enough real-world testing outside of a small variety of locks. They needed to get a manufacturer up to speed with a brand new mechanical design that was all in-house (not many existing parts were used, it was mostly custom made). People wanted the product so much, that the early units that went out ran in to many issues, things that were not learned until it was almost too late.
Having used a crowdfunded unit (briefly), I can tell you this was the case. Alignment was tricky, connectivity issue, and reflashing the firmware, reflashing the Bluetooth stack, adjusting power save settings, adjust power control settings, and more. It took me around 16 hours to get it working properly, and that was towards the end of active shipments. I hate to think about what everyone else before me had to deal with.
The key point here was the software. The production details tell us that the Bolt uses an all new circuit board, but the software is mostly intact and rolled out. The locks will mechanically work with a key, meaning that you would never be locked out.
For physical design, as @cameron said, there are some small cosmetic changes that require verification. The core mechanisms are unchanged and are proven to work.
Thanks to the test work, they know the majority of the changes they have to make are firmware related, and a small revision of the circuit board antenna (which has already been put in to work).
As the circuit board is pretty much set, they are able to spin up production very quickly, and will have no issues getting them produced.
As the manufacturer they are using has a proven, working lock design, they are already producing these parts at scale, and will have no issue creating our Bolt lock units.
They want to make sure that this is all going correctly. The preview units (which were the first to be built with this whole new product) were produced not that long ago, and are already helping to make changes. Once they know it's working properly, then the production for the regular units won't take very long to fulfill.
You might say this is all that has been said before, but I felt it important to lay it all out again as clearly as I can. Sure, they may have been considering the design a while ago, but they've told us this only started coming together around the announcement in January. They've saved most of the mechanical design time by using the proven design, but that still leaves a pretty big part of launching an all new product.
All the recent updates have shown pretty good progress to me. It may be a lot harder to confirm as all the Preview testers are under a non-disclosure agreement, but there are units in people's hands, actively being used. Once Lockitron feels it's ready and safe to move ahead, you'll hear about it.
Until then, no one wants to take a risk, no one wants to have any more broken promises or be lied to, and no one is trying to do either.