In a bit of bitter irony, new Secret clearances seem to have gotten back down to the 3-6 month time frame, based on limited anecdotal evidence. Folks caught in the backlog are still lingering but at least new applications are being processed in a more reasonable amount of time.
And don’t forget, if DSS (or some newly minted DoD agency) does take over the DoD piece of investigations, then they will need to set up all those field offices and resident offices and regional offices and district headquarters etc etc etc. So that’s a lot of time energy and effort (not to mention expense) that will not directly address the massive backlog. Might even slow down those new investigations.