Somewhat unsurprised, and very annoyed.
I'll be partially unsurprised, because I've joked about Square-Enix glancing over the yard at Konami's back garden and realising that despite the move and the publicity, Ground Zeroes did well, and a better wallet fattener than if they just released Metal Gear Solid 5 in its entirety. So why not do the same? Wouldn't it also fit with one of their vague business proposals of making money out of a product they've yet to technically release? Yes it would!
Annoyed because obviously, screw this practice, especially if it's a short one, and the value for money for one playthrough is questionable. I would avoid it out of principle and wait for the full release, or a subsequent edition to have the prologue material included. Don't you dare start charging people, especially anywhere north of £10 especially, for critical storyline content that could easily have been part of the full release, for content likely to be not worth the asking price.
And if they do that, guess what? I buy FFXV for at least half its asking price. Or a third of it, preferably.
