Bill Strong

4.8 is the first version to support plugins downloading from the store. With this change, they are starting to flesh out how they plan to distribute these plugins, and their requirement for sellers.

They are suggesting as a best practice a layer that interfaces with the UE and your specific plugin, in this case, Houdini Engine. They would like to have the source code to this layer, at minimum, to ensure long term support for those that buy the plugin to have the ability to modify it for later versions of the Engine.

Of course, with Houdini, I don't think that is such a big issue, but it would be nice to be able to include support for highly customized versions of the Engines, rather than just the stock engines.

There are a lot of developers that back port needed functionality when they get close to release, rather than upgrade the engine. They back
port both features, and fixes. And they run the risk of plugins not working anymore in this situation.

I personally just stick with the stock engine for small projects, but create custom engines from master for testing things such as Hairworks. (By the way, it would be great to be able to turn Houdini Fur into Hairworks inside Houdini, hint hint.)