I'm actually very interested in this upcoming camera. The rumors of it rocking dual SD UHS-II card slots is what makes it most interesting to me: I don't want to spend money buying expensive XQD or CFexpress cards as I don't have the need for the additional speed, I'll rather spend that money on Z lenses. I do hope that it pack yet another update to the Z AF system, with class beating capabilities, and that it will soon be priced competitively against the Canon RP and Sony A7II.
Sandisk CF Express Extreme Pro 128GB 1700MB/s Read Speed, 1200MB/s Write Speed @ £259 vs Sandisk Extreme Pro 128GB SDHC Card 280MB/s UHS-II Class 10 U3 @ £271.00
Of course if you are using type 1 cards, CFE can't compete with something so prolific. But UHS-II SD vs CFExpress is a no brainer in the favour of CFExpress and that is without taking into account that the CFExpress cards (will not proven for years yet) do report in as more durable.
On a side, I will also give kudos to Nikon if they indeed maintain an EN-EL15 battery slot, as I am also invested in those and do not want to buy new EN-EL25 batteries (the ones the Z50 uses) that have less capacity.
Besides, faster SD standards have been coming up periodically, keeping the form factor up to speed with its competitors, and since it's the most widely used physical card format, it will remain the most cost-effective one for the foreseeable future. I am sure that when 8K60p becomes available in entry-level cameras there will be plenty of inexpensive SD cards available that will be able to record its throughput. In fact, the Samsung Galaxy S20 already does 8K24p with microSD UHS-III cards. You have to also consider that 8K comes with more efficiency codecs, so it's not like it has to be 16x the bitrate of a 1080p feed. SD will remain the consumer-friendly format for years to come. XQD never took off, its physical format staying alive only thanks to CFexpress rescuing it, and CF will be pretty much limited to high end applications.
If you want an SD card to match its competitors (XQD and CFExpress) you need to spend as much money for a quarter of the speed performance. A quick review of B&H will demonstrate that. The fastest write speed of any SDXC that you can buy from B&H is about 250 MB/s. For the exact same price you can buy a CF Express that is six times faster.
The ONLY use case that I can think of for SD over CF Express is when write performance is practically irrelevant. That will be fine for some entry level photographers that are fine with 25MP/s but people that care about write speed will also buy entry level cameras. Nikon will lose those sales if it doesn't cater to them. It will be more profitably for Nikon to make you pay for your cards as opposed to losing the sales of people that care about write speed to Sony and Canon.
Second, Sony A9 only uses SD UHS2 slots and are doing quite well. Canon 1dx2 still only uses CompactFlash and cfast. I don't know if Nikon's D5 is selling well or not compared to other brands. But if not, it won't be due to the card speed.
The Canon 1DX Mark II CFast 2 slot is comparable with XQD in speed.
The Canon 1DX Mark III has CFExpress and almost unlimited buffer due to it.
Same MP Same AF system Dual slots of any sort is good but no top screen and a very low res rear screen. Unless its going to be very cheap I dont get it . ( and I wont buy it )
We still may get a Z50 with a FF sensor. The rumours might be wrong or maybe that is going to be a Z4. Either way, the camera that fits my use case is not made yet.
I have been thinking that the Z8/9 is going to be the same body but "as good as a D6". The Z8 will be like a D3x and the Z9 will be like a D3s. I have been thinking for quite a while that they would do this, but these will be expensive cameras that will leave a gap between the Z6/7 and Z8/9 - unless they upgrade the Z6/7.
If the new information is not true and the Z5 is a Z50 with a ff sensor, then I have a different hypothesis.
We will see in due course.
BTW, no, your XQD won't work in upcoming CFE cameras, only the Nikon, (even that is a big IF). That's a big qualifier, and probably limited to only the immediate next version too. But that's irrelevant anyway to your original point of a high end technology will always migrate to the low end.
Because there will be Z8, and Z9. Also if there is an even lower end without EVF, though I feel it's highly unlikely at this stage. I think Nikon will only carry 3 FF Z models, at most 4.
Which brings us to the Z5's eventual pricing position in the Z system. Granted, Peter does point out that the rumored specs might or might not be correct, but most of them seem to complement each other correctly: you need the EN-EL15 in order to have decent CIPA frame numbers if it has IBIS and/or the Z6's high res EVF, otherwise, the new EN-EL25 from the Z50 would suffice, as Canon uses the M5's battery in the RP, which doesn't equip IBIS or a high res EVF. The IBIS module might not be that expensive after all, as the Sony A7II has one and they are able to sell it for less than $900, albeit this IBIS module is not as precise as the A7III's. The 3,680K-dot EVF OLED panel might have dropped in price as there are now even higher resolution panels available, and Nikon can certainly get a handsome discount thanks to the higher volumes they will be moving, also Nikon could alternatively use a way cheaper field scan LCD panel like the one introduced by Panasonic in their new G100 which is "3,680K-dot equivalent" and the image presented might still be better than the Z50's. So Nikon might be able to pull off a profitable $900 Z5 body after all while still fulfilling all the rumored specs, also all component costs might have gone down in price since Canon's RP was introduced, but in order to do so Nikon might end up cutting corners like they did with the D600, although thanks to all the quality issues that Nikon went through with the D600 and D750 they have improved their mfq. quality levels to a point that we no longer hear about duds coming out of their factories.
Anything more than that is unlikely with the current market size.