On the whole Sutherland thing, I think he's a great voice, though I only associate him to the bandanna less Big Boss/Venom Snake. Even if we were to see Big Boss playable through a costume, it just wouldn't feel right to me if its based off any other design.
That said, I'd still take his voice over ripped Brawl voice clips, since newly recorded lines make the character feel even more fresh to me. But I don't think getting Hayter to record new lines is out of the picture at all; I even remember the (cancelled) Metal gear 1 fan remake managed to get him to voice Solid Snake.
Anyway, I just saw this fanart now.
When there's another MGS game exclusive to a Nintendo console, they would definitely need to have a Splatoon side game like they did Ape Escape. It just screams for it with how stealth is kind of involved in Splatoon. Or at least get some side missions like Monster Hunter.
I dream of having Inkling and Snake released in the next dlc wave, oh cry.