I assume that what you are asking about is a connection to the home.
To come up with any sort of answer we have to look at trends. In doing this there are two important areas, what is technically possible at a reasonable price and what the end user demands.
15 years or so ago I could expect to be able to get a 56kbps connection via dial-up in my home. This has progressed to the point where I now have a 32Mbps DSL connection with 62Mbps available if a network node is close enough to my house.
Demand for bandwidth is determined by the services that I want. 15 or more years ago I could have wanted TV delivered over my phone line but it just was not available. I would have needed something in the order of 34Mbps to get this. Now, with MPEG4 we can get a TV channel in 1.5Mbps. To a great extent this has come about because of the much higher processing speeds that are available. So now I am able to get different programs on my two TVs and record 4 other programs at the same time all within 9Mbps. A VOIP phone line takes up a little bit more bandwidth and I use about 3Mbps to connect my 3 computers and a Nintendo to the internet.
I can, if I wish, have a much faster intenet connection for my computers. The thing is, the fastest things that I want to do is to download software and software updates. The available bandwidth is limited by other end of the connection.
Over all, I find that 32Mbps is quite enough for me and leaves room to improve my internet bandwidth if I want to. Who knows what new wervices may be available in the next 10 or 15 years.
