[0xbadcafebee]

I don't think it's possible to use modern HTTPS with old browsers. All the old ciphers are now insecure and obsolete. Even if you supported the old ciphers, what would be the point, since they're insecure? So just provide plain HTTP.

For the majority of users, man-in-the-middle attacks (by someone other than your ISP) will never be an issue. It's mostly a theoretical problem. Your connection at home (and your laptop) is as safe as your Wifi connection. Your mobile connection is probably more secure. And there is no hacker sitting in your coffee shop waiting to p0wn your connection to Facebook or send you a 0day. HTTPS is necessary for the whole world to trust e-commerce, but saying everything has to be encrypted is ridiculous.

The most likely MitM anyone will ever experience is DNS cache poisoning, and that's pretty rare.

[Cloudef]

There's already a huge MitM between you and the server called cloudflare