I think Calypso is not just about WordPress.com and a Front-End Desktop App, but a larger picture of the future direction the WordPress system is also taking. Seeing Calypso for .com and the REST API coming out in 4.4 is not giving mixed signals, but a unification in a single direction.

Our CTO has actually tried to dig deeper and understand the architecture of Calypso and the possible future possibilities and direction WordPress is taking. Cannot add all the points here, but the blog here This is definitely the biggest thing being talked about in the WordPress community right now Emily.

In fact, our CTO has analysed this and provided a architectural breakdown of Calypso and provide his thoughts on the future direction WordPress is taking. Could not add all points here but the blog post should be a complementary for readers here. https://goo.gl/jmYFUP could be helpful.