This is great news as it makes using multiple Ad networks easier.
Still, PubCenter is quite basic in comparison what you can get on Android and iOS. It's kind of weird that Microsoft hasn't put more effort to making PubCenter more attractive to both Advertisers and Publishers.
On Advertisers side there's lots of things missing; You can only pay per impression, not per click or per install. You can not target your campaigns other than with a Windows Phone region, so no category targeting. And you can not create your own ad! You have to select from the couple of options that they provide and those are lousy ads.
If they would improve the advertisement options PubCenter would be more interesting to Advertisers and that would also increase revenue generated for Publishers as well, it would be win-win to all. I guess we just have to wait a couple of years more...