We will get some tools, but smartthings has made it clear that they do not intend to continue hosting other people’s custom code in their cloud forever. They consider it to be a large source of the instability over the last couple of years.
We don’t yet know how they are going to handle hub connected devices, like zigbee and zwave. But for everything else, you can do pretty much whatever you want to, but you will connect to smartthings through the published API And you will host your own code to do so. Or you will be able to use the new rules API, which is a lot like webcore and much more advanced than what is in the basic app features.