I think the idea from Viofo is to have a 4K solution in every model range.
So with this they have a 4K solution in the A119 range and so dont need to expand more on that range of systems ( normally the single channel systems ) and then 2 and 3 channel in the A139 model, so if they also make a A229 PRO that will cover 4K for dual systems normally the A129 / 229 series.
The old 4K systems i assume will be phased out now, at least i personally see no reason for keeping those around, even if you could sell them at a lesser price, and so not compete with your hallmark 4K model.
In general / personally i am only interested in 2 channel systems ( front & rear ) driving ride share are illegal here so i would never get a need for the uber ( interior ) camera
I would very much be interested in a 3 channel system if i could use the 2 remote cameras as side cameras, but i think to do that good you would need to make special side camera housings, and if possible also use lenses a little wider FOV than the norm for front & rear cameras.
That way i could have such a system + a dual channel system and have full 360 coverage + redundancy on the front with 2 cameras there, i say this as in my car with its windscreen layout that would be no problem, i am aware many new cars having 2 cameras on a already " busy " windscreen is a tall order.
The main thing i think now at least in the A139 range is to have firmware's custom for every version, this way running the 2 channel version it is not just a gimped 3 channel firmware, so even if it is just 2 channels it would still have same bitrates as 3 channel model just be down 1 camera.
And of course the single channel model, that one should at least have the option for ( compared to 2 - 3 channel ) blazing high bitrates as you can spend it all on that one camera.
If your 1 channel 4K / A139 camera had the same bitrates as the 2 and 3 channel models,,,,, that would be ridiculous in my mind, and it would be a turn off for buying the system.
I would be very interested in a blazing bitrate 4K front camera, the only thing that would turn the sides of my mouth down a little might be if it was still using little memory cards,,,,, even if it supported 1TB memory cards, for such a thing i would much prefer a 2 TB NVME drive, and i also recon a fast enough one of those i could still get cheaper than a 1 TB memory card.
CUZ you would not need the very latest NVME drives for something like that, pretty far from that actually.
Just checked in 1 store ( proshop ) here, and the cheapest 2TB NVME drive is a crusial P2, the cheapest 1TB micro SD card is the sandisk ultra, both cost about 161 USD
The next cheapest 1TB micro SD card is the team group elite, but then you are a few USD more expensive, and still if they are fast enough are questionable, and you dont have to go many cards up from the cheapest ones before the price are around 268 USD and higher.
The cheap crusial P2 NVME drive are about 2000 MB/s read / write so without a doubt plenty fast.