First of all I think that is a really good question and unfortunately there is no straight answer. The question is how will the eliminate widgets and apps? It seems as though they are looking to decapitate many of the applications by allowing developers to extend Facebook to their websites or applications instead of allowing developers to bring their apps to FB. As a marketer this sucks because there are lots of great tools that enable me to create tools and applications without a lot of technical knowledge. On the other hand allowing FB users to port over data gives marketers the opportunity to understand their user's behavior in a little more detail (With their permission of course). Essentially the accessibility of tools to build FB apps has helped a lot of non-technical marketers be successful on FB. Switching to a platform that requires a more technical background will eventually push the internet back to what it once was. An internet where usability is a greater concern and the availability of data is much more diffused. This inevitably makes it difficult for marketers and painful for developers. Of course this won't happen quickly but it is one point of view.

As far as what it will do to apps overall is a different question. I don't think it will limit the creativity of marketers, but I think we will see a drop in the production and type of applications because now the development and process for developing an application will be longer. It will become longer because more effort will have to go into things like, testing, usability, and accessibility than before. With FB many of those issues are eliminated and won't have a substantial impact on the development cycle or the possible success of the applications. With the virility of the internet almost any application can go viral and be successful, but creating extra clicks and pages for users, or more technical knowledge and development time for marketers takes the internet 3 steps backwards. With that said, FB killing Apps won't kill apps in general, but it could potentially lead to users missing out on a lot of great experiences.

Generally speaking this is a good conversation topic, but this is my quick answer.