As I wrote in other threads, IMVHO next gen Sony will have to partially follow NS example. Partially as it won't have to make a totally hybrid choice, this would damage its sales in its strongest region, EU, but simply including a hybrid version in the range of next gen PS. This will require to launch it not earlier than in 2020, as even the hybrid version will have to consistently outperform base model PS4, when docked, but besides this there won't be other big obsatacles: both PS4 and XBOne use quite lightweight 2012-2013 tech AMD CPU cores, and CPU performance is the only part of performances that must be always delivered almost completely (a minor part is renounceable if there are optional services that can be turned off when undocked), while graphics can be delivered by a mobile GPU or the main APU's GPU greatly downclocked, when undocked. Great leaps made by latest AMD CPUs, GPUs and APUs make this goal easier to achieve, but it will take anyway some more years to allow mobile or ultraportable CPU cores to deliver the desired performance leap too, and some time will be necessary to devise and design the most suitable solution for graphics, either choosing AMD GPU cores that can switch between two quite different performance levels or include both a full performance mid-range GPU and a mobile one without an excessive cost increase. Quite likely, anyway, APUs with such features, just needing minor customisations for consoles, will be made by AMD for entry-level and mid-range desktop replacement laptops that won't need an additional GPU to run at full power when connected to the power grid. RAM and solid state storage won't obviously be a problem.
The problem with a hybrid SKU is that it would have no way to play the existing Bluray library, and I don't see it being a success with a digital only approach (especially in Japan).. not when game file sizes keep increasing.
If PS4 Hybrid (late 2019) exceeds Sony's expectations, then they might ditch Bluray in favor of cartridges with PS5. The downside (apart from the obvious) is the lack of full backwards compatibility some gamers are asking for. Then again, Switch and PS4's lack of BC didn't seem to harm them much. It'd make sense to go for cartridges if they plan to launch a portable SKU later down the road, wouldn't it?
Another way to go about it is to have a Bluray drive integrated into the dock, and you're given the ability to install your games into the hybrid's storage, which could require strict DRM of sorts.
Good points, and yes, BD drive will be dirt cheap by then, so including one in the hybrid's docking station, and also in the non-hybrid SKUs would make sense, also because a phisical format either for games (possibly besides not only dd, but also mini cartridges) or for movies or for both will always be welcome for all the people living in zones that won't ever have a really fast connection simply beacuse telcos don't find the investment justified by the potential audience there.
All the problems a pure hybrid approach would bring to a company that always was stronger on home consoles than on portables are more than enough to choose a product strategy where the hybrid is just one of the available SKUs.
Will there be a hybrid PS4 before PS5? I can see both pros and cons doing it, a pro, as you write, is to test the market, a con could be to spoil the novelty for PS5, two other cons are that there's little time left to design and test it and start its production and that while in 2020 or 2021 it will be easy to have all the necessary chips with the right performances, power savings and price for the new PS5, in 2019 such chips could easily deliver base model PS4 performances and with the right power consumption, but it could be more difficult to have them at a right price for a console that by then will be quite cheap, and with pootential sales left not granting the economies of scale that will be a lot easier to achieve next gen making a hybrid version since launch.
I have no sure solution, otherwise I'd try to be hired by Sony.
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