Probably not alljoyn, for a bunch of different technical reasons. It’s been available since 2016 and has very few certified devices so far.
Insteon announced a alljoyn – compatible version of their hub at the same time they announced the HomeKit version, which they still make. They sold a few of the alljoyn ones, but not many, and discontinued the line after two or three years.
https://www.insteon.com/insteon-hub-alljoyn
The Simple Deployment Winner for Now: Amazon Echo
The closest thing that’s actually being practically deployed in a significant number of global households is Amazon Echo. “Echo, discover new devices” works quite well with more and more brands every day, and has become something that many consumers look for before they buy something new. And it even works with inexpensive third-party brands like some of the Chinese manufacturers. Amazon’s customer support is also quite good.
And it can also work as a “ Man in the middle“ for otherwise incompatible devices, something that many community members are taking advantage of:
Ship a Kit options: good for home security, but may not be flexible enough for a Home Automation
What manufacturers creating systems for the DIY security market Have always done is to send you a kit of preconfigured devices to limit first time install headaches. And to strictly limit the specific brand/models that will work with their system. That tends to work OK for security systems where you have a limited number of use cases, but not for Home Automation.
HomeKit: works well for some people
If you’re willing to go to a “walled garden” ecosystem and you use iOS devices, HomeKit has been very successful in making it super easy to add devices from different brands as long as they are all HomeKit certified. And they have been improving features and device selection over time, although it’s still a small selection compared to what smartthings supports. but it’s good enough for a lot of people, particularly those who are already using iOS devices, and right now, you can do more complex logic then you can with the echo platform. And both of these platforms continue to add new features regularly.
Initially, the biggest negative with HomeKit was that very few manufacturers could meet the HomeKit requirement and those are usually expensive brands.
But after Apple changed the certifying requirements, We are starting to see more manufacturers and some budget brands like Xioami and TPlink and KooGeek and IKEA jumping on board.
certified “works with smartthings“ devices
It’s also important to remember that smartthings staff have said multiple times, including in this forum, that their typical customer has 15 or fewer devices and never uses any custom code. If you limit yourself to the devices on the official “works with SmartThings” list and you are using the new app, then installation is pretty simple. Not as good as Echo, and not quite as good as HomeKit, but much better than the old system.
The Future of Open Standards like AllJoyn, Dot Dot, Thread, etc
There are a lot of big open standards initiatives underway, and most of the big manufacturers, including Samsung, join the working groups, but they never really go anywhere. Look, it’s 2019, and we don’t even have a universal power cord standard. 
At the end of the day, these guys compete against each other, and they all have their own reasons for choosing particular features.
The most effective way to get universal standards is doing it from the consumer demand side. That’s what has happened with the echo. Over 100 million echo devices have been sold worldwide, and those customers want to see “works with Alexa” in the product description. It’s been happening with big manufacturers and little manufacturers and big Chinese manufacturers you’ve never heard of in the US. At all price points.
So that’s a good trend, and I think we will see more of it going forward. But not coming out of the initiative projects. 