I can't see them ditching Decklink cards.
That would be a Kick in the Nutz for a lot of us.
I run Vegas & Premiere Pro on the same machine and I Love it that no matter which one I'm using I still have full control over my Decklink card. I'm definitely not ready to spend the money to Crossgrade to an AJA card.
Decklink works fine for me in V8 so long as I capture with Ppro and render with Vegas. It also works fine if I capture with Vegas and render with Ppro. Do both with Vegas and it's a mess.