I remember the VAX/VMS too. But there is a difference here...back in 1980 (or so) until 1993, not many people actually owned a personal computer (especially compared to today). Since 2001-ish (when PCs first sold for under the $1000 mark), everyone and their grandmother has one...most homes have more than 1....some users even have multiple computers.I am old enough to remember when the Mainframe crowd and the VAX crowd used to say the same thing. While they still exist in the background, I don't think anyone denies those first PC's started the process. Today's tablets are the start whether people want to believe it or not.
Tablets right now are a great start...nobody denies that they have opened the doors for a new market. I really think of tablets as sub-par to PCs simply because of tablets' inherent nature of 1)small screens, 2)touchscreen, 3)low CPU power, 4)poor virtual keyboard for typing anything longer than 3 sentences.
Now...trying to convert hundreds of millions of people to tablets or handheld is not going to happen in 5, 10, or even 15 years. There are so many uses for a PC...and so many users out there that actually NEED to use something better/traditional than a tablet...whether for work or home. Add in that a tablet still costs the same or more for a nice desktop or fair Windows laptop (3 years after the intro of the iPad I will add) and you've got multiple barriers to break.
The current tablet and handheld devices will definitely expand in their functionality...but you've still got a lot of people that would feel that many features are still missing compared to a full-fledged pc (again, mice, keyboards, large monitors, storage, universal connections, open-ness)...not to mention the iPad STILL requires iTunes that, ahem, runs on a PC.
Just a guess, but looking at history of things and the uptake of the smartphones and tablets, I doubt it will take 20 years.
I disagree...if you're talking about REPLACING a PC with a tablet, 20 years will be the time. There is just soooo much lacking in a tablet as far as physical features, CPU power, and the whole touchscreen thing (which at times is sweet for tapping to read an email but horrific to actually zoom into a page, scroll around, find the correct weblink, and tap it, for example...as well as trying to edit a few paragraphs of text)
I have my iPhone 4S and love it to death...but a PC killer? No way. Not even 5-10 years from now. We have an iPad 3...same feeling. Both devices are absolutely SWEET for grabbing emails, quick web surfing, a Youtube here and there, Facetime, and looking at some pix sent via email. Every other feature on the iOS devices is just fair...nothing that would make me throw out my PCs. We're not diehard PC users, but those 3-4 features I mentioned above that are sweet on the iPad/iPhone are just the tip of the iceberg on what I, my wife, and people who work in an office use a PC for. Stuff like making PPT or Word docs, PDF files, deep calendar/email integration, virtual machine stuff, holding webinars, running business-created thick client or web-client apps (not supported on iOS), doing video editing, Camtasia, etc...simply cannot be done on tablets...even if the CPU power were there, the touchscreen interface prevents usability.
Again...love my iPhone and iPad for a few great features (and we can afford these $500+ items) but they are simply not a PC killer or even close unless all you use your PC for is reading emails and watching Youtube.