M custom data source
The AS Team have done an amazing job with Azure and 2017. However there is no support for custom data sources, which is sorely missing.
There are so many use cases (mine is below) for this and such a feature would finally enable Excel, Power BI and Tabular to use common code for data sources. This would mean less testing and more robust solutions.
The use case that I have, is to create an M data source that would let me connect to http endpoints, where the endpoint could return data in any format. For example csv, json, xml or even a proprietary binary format such as GRPC. As I cannot write a custom data source, I am forced to download the data to files, and then load the files into tabular, this file download step is unnecessary.
F Moeller commented
For ODBC driver wrapping a request for the same feature is at https://feedback.azure.com/forums/556165-azure-analysis-services/suggestions/17016100-odbc .