Im not holding my breath for WIMAX, although (correct me if Im wrong)
one wouldnt necessarily need to upgrade a computer - but just a wifi modem and card. However one should expect to upgrade computers every 5 years or so anyway.
The industry is geared up for installing it into TIVOs TVs, Computers etc and it is a fairly large group of companies working together - such as Intel, Sprint NExtel etc.. that when it does take off it might just be a disruptive technology, why would anyone want to pay for cable or dsl when you can have something 50x faster for the same price.
It would provide some other competition to the cable and telcos that always tack on some system access fee, or long distance fee to your bill. Both in Canada and the US the cable & phone companies also have been complaining about the high bandwith usage such as voip and videoconferencing and end up degrading the service unless you have a contract with them.. That would provide an alternative.
It will also give a choice to those in the country, where its not worthwhile for the telcos to put in cable or upgrade the phone lines.
It may take longer than I think, but I remember when someone told me about dsl a few years back, we waited a while to get it for - since the printing business deals with large files it certainly is handy.