I would argue that “How can it possibly take this long” in English is actually idiomatic. People that say that are seldom asking for a concrete answer that explains it, they are noting their dissatisfaction, as such I'd say a translation such as
Which is also idiomatic would fit better. It denotes the frustration of the speaker with how long it takes.
However, to literally seek an answer as to how it can possibly take this long, I would suggest a simple:
But I believe the reason this sentence does not actually translate the “possibly” is that in English the possibly itself unambiguously implies the frustration and nothing more. It makes no sense to include “possibly” when actually wanting to know something, I would argue that any open inquiry in English that uses “possibly” is not actually asking in earnestly but simply expressing frustration, and that's why I don't think there's a good way to include that part in a translation that's actually asking. As such, my translation is more so a translation of a simple “Why does it take this long to release a video game?”