The Vita is still kicking.
Right, continuing to "support" Vita (please, please, please don't cancel...) is a good PR move for Iga's team. Nintendo fans switched to Switch easily and seem to have little qualms about the Wii U being dropped, but Vita fans are still a vocal and rabid group (even though it's hard to say how much buying power they'll have a whole year from now, even today it's a question.)
It's also smart for Sony's 3rd Party Relations team to do what it can for Bloodstained and the Vita plans, since there's still ugliness over Sony's 1st Party drop. They've sadly checked out on the platform even further since the second-wind days of Borderlands and Banner Saga and such, but if the plans still hold and Sony can ensure it provides support as needed, they can call this a win.
Plugged in on life support maybe
I doubt it's really that much harder - sure, it's less powerful, but UE3 was poorly optimized on both platforms even with official support from Epic. I'd be impressed if Armature managed to achieve anything more than "ugly with frequent drops to ~20fps" on either platform.
So, the reason it was never done before is because timing and economics never worked out. (Sony put all of its Vita life support hopes on Unity instead of Unreal, and Epic never gave the system a second look for UE4 viability even when Vita was an emerging platform.) When Vita was coming up, UE3 was good enough (even that support was not wholehearted, and studios like Armature and Iron Galaxy had to do a lot to get their UE3 projects to even the criticized levels they achieved on Vita) and UE4 was still burgeoning (and using Global Illumination), and then Vita dropped out before there was ever even a thought of talking about what would happen if even the mobile framework of UE4 was tried on Vita.
But we talked about this whole thing back when Bloodstained PSV / UE4 Port was first announced, and if I recall right, it may not be as ridiculous as it sounds? Vita is clearly underpowered, but it does use a modern architecture with APIs that are clearly defined. (As I understand it, there's a good deal of similarity in library between Vita and PS3/PS4.) So a lot of the engine porting work would be in translating instructions to how the Vita would naturally handle such a task, rather than writing the tasks for the first time to Vita's understanding. Once you have the working framework, then you see what's doable and isn't, and from there you're doing engine rewrites/optimizations as well as porting the game software (cutting textures, simplifying models, dropping/changing effects, redoing the lighting model, refinements across the board, all that brute work stuff,) and that optimization work is something you'd be doing anyway when porting a game from one platform to another if the job calls for anything but baseline engine performance. Also, if I recall correctly, the engine porting didn't scare programmers as much as the RAM limitations, and what you'd have left over to run your code after porting over UE4 to Vita was the big unanswered question. RAM is a problem with Unity on Vita, and in some ways Unity might struggle even harder with a platform like Vita than UE4 as it handles things differently in ways that can leave developers stranded when juggling memory with unoptimized code/assets later in the development phase.
(*Please jump all over my ass if you are a programmer and see huge holes in my statement, I am not a programmer but I recall these UE4/Vita discussions we had back in 2015.)
Being a
good version of Bloodstained, with a framerate and any clear approximation of the graphics and loadtimes that don't put you to sleep and no bugs to crash it every 10 minutes, that's another story, but that'd be a challenge no matter what engine was used in porting this game to this platform.
