Where are the Snapcenter 4.7 and 4.8 support date milestones? I don't see these versions listed here NetApp Support Site - Software Version Support ?
You are correct, it isn't listed there. I am guessing the page isn't updated. You could just raise a ticket with NetApp to find out. If you do get an update, let us know.
Just to add to this, as a general rule we don't announce the EOS dates for Full and Limited Support until later after the release of the software product.