Certainly. Leave it free at Smashwords/iTunes/Kobo/etc. long enough, and it'll drop and stay there, at least for the US*.
Over the years, I've gathered a bunch of 1st-in-series introductory backlist novels that were freebied long ago on Smashwords from romance, mystery, and sf/fantasy authors (e.g. Stephen Berry's
The Biofab War, which first came to my attention
in 2012 and remains free to this day, price-matched everywhere†), which have since propagated to and stayed free in pretty much all the stores, and they've become my mainstays when I want to recommend quality freebie genre titles which I can be reasonably certain will still be there when the Gentle Reader finally gets around to downloading them (if ever they do).
* Very occasionally, things that were once free for years at Amazon for Canadian accounts and still remain free in other Canadian-accessible venues go up in price and this is very annoying, but seems unavoidable. However, Amazon seems very consistent about keeping US and UK store long-term freebies free.
† Well, except Amazon Canada, where once it was free but now at 87 cents, which is apparently from the 99 cent price it had before being made permanently free at Smashwords. So I think the moral of this story is to set your story to "Free" at Smashwords from the outset and try not to ever give it a price that Amazon can revert to.
But it's still free in the US and UK, if not the other specific Amazon country stores that I was able to quickly check. And they do sometimes bounce back down. Sometimes.