SM may need to stop providing these items going forward, but you as the end user do not have to give up those items if you already purchased them as part of P8. Just move them someplace else until after the update and then put them back.

Whether SM has the right to remove purchased content from your runtime is a legal question I'm not qualified to answer, but I do know you have the right to prevent the deletion. At the time you purchased P8 that content was included and you do not lose the right to use it just because SM agreed to stop including it.  

SM may argue that such content was a "free" bonus for buying P8 and they therefore have the right to take it back. But they would lose that argument. The price of P8 is considered to include all content in the installation.