My recent proposal rdylib (a variation of dylib that allows unloading DLLs), also requires properly handling of RAII.
What scoped threads/scoped tasks and unloadable DLLs all require is the concept of relative 'static. A scoped thread has it own lifetime, which is not 'static and Arc need to be customized for this to avoid being leaked. The same happen to scoped tasked. And if a DLL is unloadable, every symbol lives in that memory space should not outlive the DLL, so the DLL's 'static is also not the same as the host program's.
Therefore I see this proposal as one step towards the solution for relative 'static.