Rooting a tablet in order to hack the OS voids the warranty, and is more work than most people want to do. I'm not asking vendors to change their existing tablet lines, nor do I insist that the entire industry offer alternatives to Android on any of their tablets. But I hope someone -- either an existing vendor or a new company -- will decide to make tablets that allow optionally running a Linux distro that isn't Android, without voiding the warranty. As I learn more about Android and realize that the source code is being shared with the Linux community at large, I find the need for an alternative Linux distro not really necessary, just desirable; I'm starting to see Android as basically a Linux distro that is tailored for a particular processor and architecture -- open-source, but necessarily limited in its functionality in order to fit a fixed hardware platform. So I suppose what I really want is an easy method of either replacing Android with an alternative distro or simply adding apps that aren't in the Android app store. Perhaps at some point a tablet vendor will introduce a second, slightly more expensive, tablet line with this capability. And even I may decide that isn't important as Android matures.
As for the other items on my wish list, most of them hardware-based, I'm sure they will all be addressed as standards develop within the tablet industry. Small-screen tablets that put a premium on light weight probably won't offer USB ports or keyboard/expansion docks, but I'm hoping they will become standard on larger-screened tablets. If I'm going to carry a tablet, it's probably going to have a screen size around 10 inches; and if I'm carrying something that size, I can certainly also take along a small/folding keyboard that easily fits in the glove box or suitcase, but when unfolded props the tablet at a comfortable viewing angle.
Equip the keyboard dock with a couple of USB ports, a power supply/charger and maybe a USB-to Ethernet dongle for configuring WiFi routers (most require logging in from a wired connection), and many people will need nothing more for home and travel use. I might even have two docks -- a highly portable keyboard-only version for travel, and one with more features sitting permanently on a desk at home. While I will keep my desktop and notebook computers for the foreseeable future, I can see going to Starbucks with nothing more than a tablet, and even taking short pleasure trips with a keyboard dock in my overnight bag.