Right now I think the best thing with Gadget is that I can use it on every one of my devices and exchange song ideas and projects. Just one App - Gadget - and all Plugins as VSTs on the whole Apple ecosystem, from the iPhone via the iPad to the Mac one app. Now with the ARM Macs and the compatibility between iOS and the Mac OS I think it would be time to make one thing out of all that alltogether. Also the iApps are identical so I can hook up my iPad to my Mac and have them with bigger interfaces. It does not make sense for KORG to somehow make 'smaller' engines for Gadget it would only be additional work. Smaller interfaces, ok, but soundwise they are identical.
I don't feel the need for the legacy collection since I own Gadget Mac and have all synths as VSTs already (no Triton though).