Thanks. The actual path to take will depend on the actual paper to come. Right now, what we have is a request for a «feature» in the list compiled by P2966, and until there is an actual paper written on that one
Patrice: Part of what Jonathan is saying is that the right approach to this specific entry is not a WG21 paper; it's a vendor bug report. But only if your vendor actually has that bug, and it sounds like nobody does. So there's Nothing To Do on this entry.
But! PMR's wording used to contain dynamic_cast, until we removed it via LWG3000 in March 2018. The P2966 entry was probably brought up sometime before 2018, and should have been removed from P2966 as a result of LWG3000's resolution.