This of course needs to be discussed in the broader OpenWhisk community first, but taking dewitt's answer here into perspective (https://news.ycombinator.com/item?id=17604185) and also based on what IBM has put out in their statement a possible interaction could be to layer OpenWhisk's higher level abstractions and multi-tenancy features over the knative stack and use the latter as an "execution-engine".

In technical terms, OpenWhisk's invoker system could be replaced by knative, keeping the API/Controller bits stable to still support the notion of actions/triggers/rules/sequences/compositions you name it.