Yep, the endgoal is mobile phones and game streaming, along with gamepass.
Streaming will be one of many options. It allows Streaming big AAA games on any device (If allowed) and by doing so, will result in bigger sales outside the console market walls.
Mobile phones is only part of it. PC is their major focus since Windows is MS biggest selling product. More games for Windows PC = more sales for MS. Xcloud will make Streaming games on all devices possible but their main focus is PC gaming and always will be. Very smart move.
They have the studios to drive the quality. MS will be the first to enter a full subscription model in the near future and one day Sony will follow suit once they start noticing the results from MS. Just like how they saw the results of Xbox Live and followed with their own pay wall model.