The technology has existed for many years. I worked with a client over ten years ago who sells this kind of equipment.
Wings of Glory planes are very nicely done in the main.
In terms of actual figures in say 10 – 28mm it can be done already but I suspect the investment is high. What I think it would need is for say the Perrys to produce single piece plastics in march attack pose that can be painted/ printed by an automated process.
Price point – no idea but I've long thought that this will be the next big step forward in the way that 28mm plastic multi-part figures were.
As to the period – I'd suggest that French Napoleonics in coats would be a good bet or ACW as the uniforms for all of these are relatively simple and they could all sell in large numbers. I think it will be a very significant advance since it'll fundamentally change the mindset of many.
For example, these days when considering a new period most will consider if they have the time to paint them, remove that from the pre-diving in decision point and a different set of questions emerge. For me I don't start new periods as I don't have the time to paint armies from scratch any more. Remove that issue and I probably would.
Probably the principle new deciding factor would become can I afford them? If you could literally buy a pre-painted ready to play figure for say £1.00 GBP that rather alters the time barrier to starting new period. Figures could be moulded on a 15 x 20mm base ready to slot into a movement tray so there would actually be no work required. The hobby might then shift so rather like we do conversions, folks would get into improving the standard factory paint finish. So a starter army in pre-painted/printed plastic might cost £200.00 GBP for the bulk of the infantry with others coming from metal ranges. I suggest the £1.00 GBP a figure since plastic unpainted is about £0.45 GBP per figure. The price point of the coloured plastic could work out to be less than unpainted metal…
For a couple of hundred quid I could literally double the size of my table ready Sudan army that has taken me years to paint with just a few mouse clicks.
Then I think we'll then see the big armies that the move to 28mm plastic was supposed to herald. I think it hasn't really done so as the figures were made too complex in needing fiddly assembly and that has actually slowed down the process, so while the raw material (figures) has dropped i.e. plastic vs metal, people still can't churn them out any faster than metal castings.
I'm certain we will see pre-coloured plastic 28m historical figures. When? I've no idea but at a guess within ten years. If the Perrys want to invest in the future and to reduce their tax bill it would be worth them investigating.