SO even with some pretty big changes, there are some that I believe would be over the top for a tablet. One of the beauties of the tablet would be destroyed if you have external monitor support. The fact it has such long battery life would be diminished to unusable levels in my estimation. Other MultiTasked items may cause similar reductions in a Tablet of any make's battery life and long term usability. So I think the limitations would be met long before all the wish list could be filled. Even the external hard drive scenario tears apart the whole concept of battery life. If it could access files wirelessly that'd be plenty, but driving the hard drive through its on board power would be too much to ask. Maybe a SD card or USB Stick... and of not too large capacity might be do-able over all, but everything everyone seems to ask for would be counter to what the iPad has going FOR it. Monstrous capabilities exist... for a Tablet... Laptop ability? maybe not, depending on what you intend to replace. Base model HP laptop would easily be a good example of something a lot of people could replace with an iPad. But generally people who buy high end laptops are power users, while the rest are just casual users mostly.
I buy High end (for my wallet) at around $3k per laptop, and could easily go higher, but find *that* my sweet spot for dependability and power and ability. I buy them for their superior hardware so I don't have to buy a new HP base model every couple of years or less to keep a decent computer around. I buy with mid level Hard drives and mid level RAM so that I get somewhere near gaming quality machines, so they will last longer for my "very average" use. I get as much as 9 years from a Laptop when I buy... I trade up a little sooner at times... but I don't like buying new very often.
Using some basic deduction, iPad will never be a laptop. But could be a replacement for someone who isn't in need of a full on DESKTOP... but a "light user" type laptop it could replace. Keep in mind, a Laptop is a Trade off from a desk top to begin with. I never understood having 10-12 or more windows open with 30 tabs per window etc... that seems to me to be an immense problem that someone with ADD would be wild about, but would also have a zero work ethic and even more zero of a productivity level... spending all day just flipping from one tab/window to the next would close off productivity that most would find necessary to actually make money. Yeah... a couple or even a few might be useful from tab to tab or window to window, if both could be visible at the same time, but the numbers I see often on here, I can only imagine someone who is marginally productive at best, and likely just someone who blows smoke and hides their unproductive behavior with some other mirrors...
It matters not how powerful the hardware, running it at full tilt would render it totaled from overheating eventually. Yes... iPad has some impressive hardware... but I believe one of the reasons the iPad in general is so hardware proud, is to have huge overhead in usable processing power so it is not taxed to a heat level that is devastating to the system. I haven't seen Apple ever explain why they have such awesome hardware but allow marginal capabilities with it... but somewhere in there, you have to know they have a clue. Some will argue that Apple doesn't have a clue... but I'm betting on the company that makes the stuff... not a bunch of arm chair QB's.
Since there's really no such thing as a cheap complete Apple Computer (complete, no matter the model or type), the iPad is not really competitive with any maker/brand of laptop. Some of Apples Tablets are as expensive as their own laptops... It is, however a great competitor for other tablets to compare to... as far as quality and ability... and generally speaking, will better any it is put up against in most any category... most. There's no other "tablet" as such, that supports external monitors and hard drives without sacrificing their power to the parasite item... so no one really wins over apple on that either... The very biggest item Apple is messing up on, that all others have handled, is their resistance to Adding SD cards for file capacity... The second one is UI... They need a mouse interface. Neither of these would really be hugely problematic for their hardware or battery life, but they refuse to oblige a growing number of us whiners who want those things. Apple's File system and manager sucks, but I have gotten used to it and can now manage using their "finder" and a second "freeware" file manager (Commander One) to deal with it... Their file system is truly lacking in many ways. I know what it's like to have a decent file manager, and crave a better app for that within ANY apple product... don't care if apple makes it or someone else... there HAS to be a better way... but I'm still searching for it. and I would PAY WELL for one that meets my expectations.
The Comparison is truly Null to begin with, but a fun exercise in futility... the concept is great, but the variations are too, too many to have a solid pat answer to the question "Can an iPad replace a laptop?" The answer, quite Plainly is "YES" and Obviously "NO" depending on your personal situation, needs, habits, expectations, and for some, the money.