Microsoft tend to state that they run a customer driven product strategy based on customer feefback. This means that the days of product and marketing strategies which are focused on the longterm are not a focus as much as they used to be for server based products.
That said there have still been some whitepapers which are relevantto help us understand the direction of travel for Microsoft.
Azure Integration Services Whitepaper
This whitepaper outlines Microsoft thinking about using resources on Azure such as Logic Apps, Event Grid, API Management and others to solve integration problems.
In late 2015 Microsoft published a whitepaper called Integration -> Evolved. This paper outlines some of the thinking around BizTalk, Logic Apps, Cloud and other integration related things. This was a strategy Microsoft has followed to some degree. It is noted that as time passes new opportunities and challenges emerge but in general I think this paper is still good reading to understand some of the background thinking even if the execution has in places changed since the paper was written.
The link below is a blog article where BizTalk 360 provided an interpretation of the paper and you can also download the original paper from this article also.