sure.

1) this describes MS Office Online's ability to open a doc off a URL. however, it explicitly says it needs to be a public doc. this does suggest that Office Online may have paid features allowing one to edit docs off a URL or will in the future support authorization:

https://blogs.office.com/2013/04/10/office-web-viewer-view-office-documents-in-a-browser

2) I think the browser plugin is the most promising route for this. If you install this chrome plugin, when you try to open/download office docs they will automatically open in chrome/google docs:

https://chrome.google.com/webstore/detail/office-editing-for-docs-s/gbkeegbaiigmenfmjfclcdgdpimamgkj?hl=en

it's not LK specific and doesnt appear to allow editing. still kinda useful. saving would be important though.