From the blog post:
The Salesforce1 Mobile App sets a new level of speed and flexibility for CRM— by empowering users to run their businesses from their phones with powerful tools that work in the cloud, keeping them up-to-date with whatever real-time data they need. Once connected to Continuum, the Salesforce1 Mobile App transforms into the Salesforce Lightning desktop experience, empowering users to manage opportunities. And with customization features, you can make your Salesforce work the way you want it to.
The new Salesforce Lightning for Continuum is the latest integration between Salesforce and Microsoft designed to empower joint customers to achieve more, from anywhere. Previously announced integrations from Microsoft and Salesforce designed to help companies connect with customers and collaborate more effectively include: Salesforce Lightning integrations with Skype for Business, OneNote and Delve, and Salesforce1 Mobile App for Windows 10.
This is the sort of universal environment that Windows 10 Mobile and Continuum were designed for, of course. You can absolutely imagine a salesman with their Windows 10 Mobile phone as their primary computing device and plugging in to 'hot desk' at depots and offices around a country. Yes, it's still a bit of a niche use case, but a lot of the business and enterprise world goes unnoticed by consumers - Salesforce.com has over 100,000 customers (i.e. companies) around the world, so multiply that figure by (say) a factor of 10 to cover those companies' mobile sales staff and you're already at 1,000,000 potential users.
More like this though, Microsoft, more examples of how your end to end vision pans out and how people might use Continuum.