Not going to happen for a long time
As many people have already said, there are to many factors that would have to be addresses before something like this happens, probably the most important would be budget, Most businesses would not want to overhaul there entire IT department, I mean I, like many have a tablet that I use for business, but I still have a computer in my office.
Obviously the need for more tablets would require more production which would probably lead to more lemons or bad parts. Right now if I have an issue with hardware I call dell, I tell them the issue and then if a part is needed, they send me the part, I open up the PC and replace the part, sure you can do the same with a tablet, but lets face it a tablet is not made to be cracked open, parts for a tables would also be impossible to come by. You cannot upgrade a tablet, you might be able to expand the storage but that is also limited to 32gb right now, which I might add is very expensive for the amount of storage you get.
Maybe like me other companies will give the tablets to people who are on the road a lot, or need to work at home, but as far as replacing an office PC, it is going to be a while before we see this transition.
The old saying goes "if it ain't broke, don???t fix it" businesses are having a hard time moving away from windows XP, so moving to Windows 8/Android or IOS would be a risk and if I have learned anything in the business world it is that risks, especially one this big is probably a risk that owners and managers will not take unless they can be sure 100% that the tablet is compatible with all hardware and software needed. All the data is 100% secure. And that doing the upgrade would not blow the budget.
