More on that:
Companies won't pay for infinite bandwidth, so they will throttle you eventually.
TCP_WINDOWS_SIZE will put a maximum on how much you can download based on how far away the server is. Anything more than 20 to 30ms and it won't be much faster than what we have today.
Anything that is encrypted is limited to the computational capacity of the CPU, unless you have an encryption acceleration chip. Around 25 to 35Mbps depending on the encryption method and how much load that crypt takes. More secure means more CPU, right now arc_four being the fastest, but least secure.