Good call on the thread move, got a little off the when will we see product over to and what if we see product there.
Ok, now to your points, and to Alexa, let's start with architecture. Most individuals will have architecture as follows when they deep dive into IoT, and when more consumers get involved:
Amazon Alexa / Google Home (Voice Layer)
Samsung SmartThings / Wink / Vera (Control Layer)
/ | \
Thing 3rd Party Hub Thing
3rd Party Things
Now that this is out of the way, more to companies and integration.
While you are correct those locks are Zigbee or Z-Wave that makes their lives simpler, and they have gone the slightly extra step of being in the app so they can be added manually, have connection instructions, and buy now links. Other more generic Z-Wave devices like the Econet EBV105 valve I recently picked up are slightly different Z-Wave in that they just show up as . But these are both irrelevant here as Lockitron is not Z-Wave and not like any of these products.
As Lockitron will supposedly have it's own bridge, this is where the integration would happen and not with the lock. When josh mentioned Hue, it is one example. SmartThings hub and the Hue bridge speak to each other over the LAN after button pairing, this is an approach, this was community developed. This same approach was that used by Chamerlain/Liftmaster where they have their own hub, but a clever coder made his own smart app and device handlers to allow tying into other things, https://github.com/brbeaird/SmartThings_MyQ this was also not developed by the manufacturer or Samsung. The Sonos integrations have actually been developed by the Samsung SmartThings folks with collaboration of Sonos, they allow limited usage outside of Sonos primary application, such as volume control play pause and track forward, offering limited control. This same approach was that used by Chamerlain/Liftmaster where they have their own hub, but a clever coder made his own smart app and device handlers to allow tying into other things, https://github.com/brbeaird/SmartThings_MyQ this is not by the manufacturer or Samsung.
My favorite, and the one that would be best equated with Lockitron would be like the folks of AlarmDecoder did for their AD2PI appliance. They created their raspberry pi based device, they created their API, and went the step further and also released https://github.com/nutechsoftware/alarmdecoder-smartthings on github which provides the device handler and smartapp for their product and their api they know intimately instead of making somebody off the street have to put it all together. It provides the ability to arm disarm, such as you would have lock / unlock. All of the fancy stuff would remain in the lockitron app and on your web page.
Perhaps the dkirker stuff still works, perhaps one of the folks that actually got a bridge will release something on github by the time the rest of us finally get our hubs. Or perhaps Lockitron can pick this up?
As for Alexa, or Google Home for that matter, those that make the home automation brains are already on that, wouldn't it be more low hanging fruit dealing with the brains which will then achieve the harder integration with the voice services with their larger budgets/teams of coders?
Of course not having the Bolt, and even less likely to see the bridge any time soon I am not in a position to deep dive into the API to see what is required here, nor be able to perform the coding and testing required to get things going and then unleash it for all of your customers to use.