As far as I understand the furthest support for Windows 7 is for the professional, and it will go to 2020. Considering Microsoft has prolonged the [security] support for XP, I would trust they will extend security support to at least 2020 for 7, probably further. If not otherwise, they will do it due to their Company Contacts.
I find it hard to believe that Microsoft will cut connections at first possible point. Doesn't sound very plausible. Windows 7 will most probably will be supported 'til 2025. Maybe not Home Versions, but who knows?