Yea I'm trying to wrap my head around this myself because I thought Vegas had that capability already. I understand in context with 4K tvs and standard hd signals "up converting" to simulate a 4K experience, but can someone clarify what this means in an NLE that edits 4K already?
It would mean the ability for Vegas to ingest lower resolution and output 4K from that source material. In general, upscaling is converting from a lower resolution to a higher resolution, and this applies to Vegas' use of the term as well.
Now ... how well, or even how, Vegas 14 will be able to do this is still unknown.