Re: the ramifications of what this really means.
I disagree with your conclusions, but I think you have a point.
Don't forget Windows 10 users can revert to the previous OS, providing they have the install media.
I don't believe MS will try to charge for any existing 10 installations after July.
However I could quite see this as being an attempt to move in that direction.
They could easily start OEMs shipping home users with a Win 10 core OS, which required a subscription to give it a full feature set. (Businesses already have the choice of renting or buying, so they might just play with the pricing for them.)
The free versions for a year could easily be a loss leader.