Updated It appears that Nikon very soon (early December November) will issue a firmware update for the Zfc that provides support for the EN-EL25a battery. Thing is, an EN-EL25a battery doesn't currently exist, though recently I've noted that some third-party batteries are referring to "EN-EL25 and EN-EL25a compatibility" in their ads, so something's afoot.
Most previous "a" releases of a battery have boosted the capacity of the battery, as does this one (the EN-EL25a goes up 100mWh in capacity from the original). Some of the third party batteries already do provide extra capacity, though you have to read the voltage, mAh, and wattage values carefully to assess that.
Still, the fact that we appear about to get a new version of the battery used in the DX bodies—and which requires a firmware update for existing cameras to use—seems to imply that Nikon may be about to release a new DX camera, or at least tweak an existing one (Zfc). In the past, new batteries have tended to be accompanied by new cameras.
As I've noted elsewhere, the Z50 is a particularly interesting problem for Nikon. In about a year, the EU would not allow sale of a Z50 due to the fact that it doesn't comply with the full set of EU regulations that have been layered up recently. In particular, the "common charger" mandate, which dictates that a digital camera that directly supports recharging must use USB-C Power Delivery. The current Z50 can be charged in camera, but the charger for that is the EH-73P, which is USB-2 to USB microB, which won't be allowed after December 28, 2024 in Europe. (I'll repeat what I've written elsewhere: I originally thought that the "common charger" mandate had grandfather clauses in it that would allow continued sales of product past the regulation going into affect, but it doesn't. Thus a different EU regulation that defines "new" comes into play, and a lot of products are probably going to go off market in Europe in 2025 because of that. It's one reason why Apple was objecting to the "common charger" regulation, for instance, because Apple likes to keep three generations of iPhone on the market, and two of them might still use Lightning connectors.)
We can all speculate what a Z50 II (or Zfc II) might be comprised of, but there's one really simple path that would completely change the experience: stick EXPEED7 and USB-C into the current camera(s). That's it. Suddenly, you'd have better autofocus, better internal video capabilities, and additional potential features, even if the same image sensor, shutter, and viewfinder are used. This is what the Zf did compared to the Z6 II, so why wouldn't Nikon continue that approach?
I used to really like the Z50. Back when it came out in 2019 it was one of the best US$1000 crop sensor mirrorless options you could get. Things have changed since then, of course. Two years later Nikon provided a few minor tweaks that would have kept the Z50 more current, but they did them in the Zfc model instead of a Z50 II. Fujifilm's recent X-S20 is arguably a better camera now, and Canon's recent R50 and R7 also bracket the Z50/Zfc, putting more competition on those DX models. Adding EXPEED7 on its own probably is enough to hold serve, which is why I mention that simple path of updating Nikon's first DX model.
Nikon's surprised us more than once in the Z System camera sequencing, so without clear inside info—which I currently don't have for the DX models—I can only speculate. It seems clear to me, though, that Nikon needs to do something in the DX space soon or risk just losing traction there. I, for instance, have been using an X-S20 instead of my Z50 since that Fujifilm appeared. The Fujifilm a bit bigger and heavier, but it offers a fair amount of things that I'd have wanted in a Z50 followup at this point.
