aye4design, I’m not too sure I can entirely agree that Universal Design is an achievable goal, while I (as an accessibility specialist - of sorts) do entirely agree with the same principles as yourself it feels rather foolhardy to proclaim that the methodology put across by universal design is in-fact achievable (where as Tommy’s older but studier principle of access now, graceful later is much better in respect to implementable potential). One thing we as accessible designers tend to forget is that accessibility is about ALL potential inhibiting factors whether a disability of human or machine (used by human), as such unless you have a medical degree, are a trained psychologist and have the entire medical vocabulary to take into account any possible disease, condition, affliction, impairment or circumstance which may prevent someone using a website when they feel or wish the need to, it’s wrong to justify that such widespread design is even possible. It’s physically impossible to account for every kind of disorder that may cause some amount of friction or inhibition and as noble as universal design is as a concept of “something everyone can access and use equally”, the laws of nature, science and computing just show us that equality is impossible… of course we can aim for the best and most widespread basis of potential friction (and inhibitors) but it’s just a bit too much to design for everyone because in a certain respect… everyone is disabled by something. 
In another thread (I’ll digress here as it’s important to my post and more useful here) “Checking the numbers” you made the following post…
This is a very real misconception (as denoted above), the amount of people with a disability is significantly higher than those without… if you take into account every possible situation where someone may be (in a respect) disabled or unable to browse a website as effectively as another person… whether physically, intellectually, emotionally, socially, psychologically, conditionally or mechanically, it’s probably closer to 99% of the world population who fall into that category. We talk about physical disability like it’s only a remote amount of people, but just look at the amount of people who have accidents where their limbs may break, sprain or be injured (for a short period of time), very few web designers account or use those as part of the stats even though their just as debilitating as fully fledged limb loss… just on a part time basis. If there’s one thing I like to preach about accessibility it’s that you, I and everyone else needs to stop thinking of disability as a numbers game of minority reports. EVERYONE on earth could be qualified as having some kind of factor which disables or inhibits their actions… whether it’s someone with an incurable disease or just someone trying to visit a website when their drunker than an Irishman. Disability is everywhere and affects everyone, sometimes it’s temporary, sometimes it’s permanent, but in all cases it’s accountable and should be recognised… and thus, true Universal design (IMO) is nothing more than a pipe dream.