DX12 and multi-GPU mix and match

I keep reading that the DX12 API will allow for "multi-GPU" configuration. It says you can have an AMD and NVidia card work together. Would this mean I could have a GTX 970 (current card) and get the upcoming GTX 1080 and have them pugged into my motherboard without a SLI bridge? They ( multiple articles) are not very clear on how it can work. I was able to pick out a laptop example where you can take advantage of the integrated GPU and the Discrete GPU at the same time.

Can anyone clarify?

It will only work if dev's code their games/engines to use SFR(split frame rendering) DX12 hardware usage is almost all about dev's coding abilities.

@04dcarraher: i see, thanks.