Hi there,
I'm not in a position to comment on VSC plans, but I don't believe our usual practice is to support multiple generations of products in such a way.
I'm more interested in how you're using VSC right now - are you using it to make quiesced snapshots of each VM? without any form of snapmirror/snapvault? If so, Veeam might be a good option to look at. There is a free version which has very good functionality.
Otherwise, just taking snapshots using the built in snapshot scheduling of ONTAP is always an option. I ran a 1800 VM environment like this for several years - the VMs were crash consistent (vs quiesced), but in those three years we only once had an issue where the most recent snapshot did not work.