Ignoring any financial gain from registrars, Nominet or speculators, my thoughts after the webcast are more or less unchanged.
.co.uk has been sold for years (long before Nominet) as THE business domain for the UK, adding .uk into the equation just confuses things for consumers and business. Whether or not it is technically required, people will feel that they must have the .uk (just as they currently do about the .com) ending up with a large duplication between .co.uk and .uk. Consumers tend to follow the popular trends so it only takes a bunch of non-technical people to blog / facebook / tweet that .co.uk is being replaced by .uk and a very large proportion of the Internet users will agree.
If we sell / give out all the new .uk's where will Nominet get future growth from? Once all the brands and existing .co.uk's have had their pick, we'll be more or less in the same situation as we are now with choice of name - all the good ones have gone and are with speculators or are in use and it will be down to the same available names regardless of where they lie under the .uk structure, there are simply no more combinations of trade / service / location under .uk than there are under .co.uk. By keeping at 3rd level, we can open up new 3rd levels making more combinations or words available. An example given was the potential .london TLD, surely if Nominet opened ".london.uk" then this would be a viable alternative to .london and would help to bring revenue to Nominet, by simply selling "london.uk" they would get just the single £20 instead of potentially thousands of xxxxx.london.uk customers.
We already have a lot of UK business already taking .com names and simply forwarding the .co.uk to the .com, so what's to suggest that we're suddenly going to get a log of .com's redirecting to .uk and actually promoting the "UK" in the .uk?
If this was to go ahead, why should trademark holders get first dibs as to what they want? Surely any trademark holder who had a case for the "leading UK business domain" would have already put their IP lawyers and / or DRS'd the current .co.uk, anyone who doesn't already have the .co.uk either has weaker rights or has chosen not exercise their rights. Direct.UK is not anything new, it is being presented as an additional part of the whole .UK structure for business, so is a sunrise actually needed?
IF it has to go ahead, I personally like the idea of pushing the current .co.uk's to additionally resolve as .uk for the next few years and then those who want to keep the .uk can choose to renew either at the end of the dual resolution period or renewal period (if the .co.uk is registered for longer than the dual resolution period)